From 4e34e03dd443f0997a0bab4f3434567edc4f8f89 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Fri, 29 Apr 2016 14:24:10 -0700
Subject: [PATCH] xl/fs: Split object layer into interface. (#1415)

---
 access-key.go                                 |  22 +-
 accesslog-handler.go                          |  20 +-
 api-router.go                                 |   2 +-
 auth-handler.go                               |   9 +-
 bucket-handlers.go                            | 123 ++--
 bucket-policy-handlers.go                     |  39 +-
 bucket-policy.go                              |  79 +--
 certs.go                                      |  20 +-
 config-migrate.go                             |  41 +-
 config-old.go                                 |  37 +-
 config-v4.go                                  |  36 +-
 config.go                                     |  30 +-
 ...pi-multipart.go => fs-objects-multipart.go | 331 ++++++-----
 fs-objects.go                                 | 333 +++++++++++
 httprange.go                                  |  28 +-
 logger-console-hook.go                        |   5 +-
 logger-file-hook.go                           |   9 +-
 logger-syslog-hook_nix.go                     |  15 +-
 logger-syslog-hook_windows.go                 |   4 +-
 logger.go                                     |  27 +-
 logger_test.go                                |   3 +-
 main.go                                       |   2 +-
 notifier.go                                   |   5 +-
 object-api-getobjectinfo_test.go              |  42 +-
 object-api-listobjects_test.go                |  51 +-
 object-api-multipart_test.go                  | 120 ++--
 object-api_test.go                            |  11 +-
 object-handlers.go                            | 118 ++--
 object-interface.go                           |  43 ++
 object-utils.go                               |  50 ++
 object_api_suite_test.go                      |  44 +-
 pkg/quick/quick.go                            | 162 +++---
 fs-dir-common.go => posix-dir-common.go       |   0
 fs-dir-nix.go => posix-dir-nix.go             |   0
 fs-dir-others.go => posix-dir-others.go       |   0
 fs-dirent-fileno.go => posix-dirent-fileno.go |   0
 fs-dirent-ino.go => posix-dirent-ino.go       |   0
 fs-utils.go => posix-utils.go                 |   0
 fs.go => posix.go                             |   2 +-
 routers.go                                    |  32 +-
 network-fs.go => rpc-client.go                |   4 +-
 ...pc-datatypes.go => rpc-server-datatypes.go |   0
 storage-rpc-server.go => rpc-server.go        |  11 +-
 server-main.go                                |  62 +-
 signature-jwt.go                              |   9 +-
 signature-v4-postpolicyform.go                |  31 +-
 update-main.go                                |  53 +-
 utils.go                                      |  10 +-
 web-handlers.go                               |  30 +-
 web-router.go                                 |   2 +-
 xl-v1-common.go => xl-erasure-v1-common.go    |   0
 ...eatefile.go => xl-erasure-v1-createfile.go |   0
 xl-v1-errors.go => xl-erasure-v1-errors.go    |   0
 ...1-healfile.go => xl-erasure-v1-healfile.go |   0
 ...1-metadata.go => xl-erasure-v1-metadata.go |   0
 ...1-readfile.go => xl-erasure-v1-readfile.go |   0
 xl-v1-utils.go => xl-erasure-v1-utils.go      |   0
 ...itcloser.go => xl-erasure-v1-waitcloser.go |   0
 xl-v1.go => xl-erasure-v1.go                  |   9 +-
 xl-objects-multipart.go                       | 531 ++++++++++++++++++
 object-api.go => xl-objects.go                | 205 +++----
 61 files changed, 1815 insertions(+), 1037 deletions(-)
 rename object-api-multipart.go => fs-objects-multipart.go (55%)
 create mode 100644 fs-objects.go
 create mode 100644 object-interface.go
 rename fs-dir-common.go => posix-dir-common.go (100%)
 rename fs-dir-nix.go => posix-dir-nix.go (100%)
 rename fs-dir-others.go => posix-dir-others.go (100%)
 rename fs-dirent-fileno.go => posix-dirent-fileno.go (100%)
 rename fs-dirent-ino.go => posix-dirent-ino.go (100%)
 rename fs-utils.go => posix-utils.go (100%)
 rename fs.go => posix.go (99%)
 rename network-fs.go => rpc-client.go (98%)
 rename storage-rpc-datatypes.go => rpc-server-datatypes.go (100%)
 rename storage-rpc-server.go => rpc-server.go (96%)
 rename xl-v1-common.go => xl-erasure-v1-common.go (100%)
 rename xl-v1-createfile.go => xl-erasure-v1-createfile.go (100%)
 rename xl-v1-errors.go => xl-erasure-v1-errors.go (100%)
 rename xl-v1-healfile.go => xl-erasure-v1-healfile.go (100%)
 rename xl-v1-metadata.go => xl-erasure-v1-metadata.go (100%)
 rename xl-v1-readfile.go => xl-erasure-v1-readfile.go (100%)
 rename xl-v1-utils.go => xl-erasure-v1-utils.go (100%)
 rename xl-v1-waitcloser.go => xl-erasure-v1-waitcloser.go (100%)
 rename xl-v1.go => xl-erasure-v1.go (98%)
 create mode 100644 xl-objects-multipart.go
 rename object-api.go => xl-objects.go (53%)

diff --git a/access-key.go b/access-key.go
index a4d2a1aea..0782836df 100644
--- a/access-key.go
+++ b/access-key.go
@@ -21,8 +21,6 @@ import (
 	"encoding/base64"
 	"fmt"
 	"regexp"
-
-	"github.com/minio/minio/pkg/probe"
 )
 
 // credential container for access and secret keys.
@@ -52,19 +50,19 @@ var isValidAccessKey = regexp.MustCompile(`^[a-zA-Z0-9\\-\\.\\_\\~]{5,20}$`)
 // mustGenAccessKeys - must generate access credentials.
 func mustGenAccessKeys() (creds credential) {
 	creds, err := genAccessKeys()
-	fatalIf(err.Trace(), "Unable to generate access keys.", nil)
+	fatalIf(err, "Unable to generate access keys.", nil)
 	return creds
 }
 
 // genAccessKeys - generate access credentials.
-func genAccessKeys() (credential, *probe.Error) {
+func genAccessKeys() (credential, error) {
 	accessKeyID, err := genAccessKeyID()
 	if err != nil {
-		return credential{}, err.Trace()
+		return credential{}, err
 	}
 	secretAccessKey, err := genSecretAccessKey()
 	if err != nil {
-		return credential{}, err.Trace()
+		return credential{}, err
 	}
 	creds := credential{
 		AccessKeyID:     string(accessKeyID),
@@ -75,10 +73,10 @@ func genAccessKeys() (credential, *probe.Error) {
 
 // genAccessKeyID - generate random alpha numeric value using only uppercase characters
 // takes input as size in integer
-func genAccessKeyID() ([]byte, *probe.Error) {
+func genAccessKeyID() ([]byte, error) {
 	alpha := make([]byte, minioAccessID)
-	if _, e := rand.Read(alpha); e != nil {
-		return nil, probe.NewError(e)
+	if _, err := rand.Read(alpha); err != nil {
+		return nil, err
 	}
 	for i := 0; i < minioAccessID; i++ {
 		alpha[i] = alphaNumericTable[alpha[i]%byte(len(alphaNumericTable))]
@@ -87,10 +85,10 @@ func genAccessKeyID() ([]byte, *probe.Error) {
 }
 
 // genSecretAccessKey - generate random base64 numeric value from a random seed.
-func genSecretAccessKey() ([]byte, *probe.Error) {
+func genSecretAccessKey() ([]byte, error) {
 	rb := make([]byte, minioSecretID)
-	if _, e := rand.Read(rb); e != nil {
-		return nil, probe.NewError(e)
+	if _, err := rand.Read(rb); err != nil {
+		return nil, err
 	}
 	return []byte(base64.StdEncoding.EncodeToString(rb))[:minioSecretID], nil
 }
diff --git a/accesslog-handler.go b/accesslog-handler.go
index 7a0211009..36812f5c8 100644
--- a/accesslog-handler.go
+++ b/accesslog-handler.go
@@ -22,8 +22,6 @@ import (
 	"net/url"
 	"os"
 	"time"
-
-	"github.com/minio/minio/pkg/probe"
 )
 
 type accessLogHandler struct {
@@ -60,14 +58,14 @@ type LogMessage struct {
 
 func (h *accessLogHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	message, err := getLogMessage(w, req)
-	fatalIf(err.Trace(), "Unable to extract http message.", nil)
-	_, e := h.accessLogFile.Write(message)
-	fatalIf(probe.NewError(e), "Writing to log file failed.", nil)
+	fatalIf(err, "Unable to extract http message.", nil)
+	_, err = h.accessLogFile.Write(message)
+	fatalIf(err, "Writing to log file failed.", nil)
 
 	h.Handler.ServeHTTP(w, req)
 }
 
-func getLogMessage(w http.ResponseWriter, req *http.Request) ([]byte, *probe.Error) {
+func getLogMessage(w http.ResponseWriter, req *http.Request) ([]byte, error) {
 	logMessage := &LogMessage{
 		StartTime: time.Now().UTC(),
 	}
@@ -103,9 +101,9 @@ func getLogMessage(w http.ResponseWriter, req *http.Request) ([]byte, *probe.Err
 
 	// logMessage.HTTP.Request = req
 	logMessage.Duration = time.Now().UTC().Sub(logMessage.StartTime)
-	js, e := json.Marshal(logMessage)
-	if e != nil {
-		return nil, probe.NewError(e)
+	js, err := json.Marshal(logMessage)
+	if err != nil {
+		return nil, err
 	}
 	js = append(js, byte('\n')) // append a new line
 	return js, nil
@@ -113,8 +111,8 @@ func getLogMessage(w http.ResponseWriter, req *http.Request) ([]byte, *probe.Err
 
 // setAccessLogHandler logs requests
 func setAccessLogHandler(h http.Handler) http.Handler {
-	file, e := os.OpenFile("access.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
-	fatalIf(probe.NewError(e), "Unable to open access log.", nil)
+	file, err := os.OpenFile("access.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
+	fatalIf(err, "Unable to open access log.", nil)
 
 	return &accessLogHandler{Handler: h, accessLogFile: file}
 }
diff --git a/api-router.go b/api-router.go
index 987cf2d46..ec19fd504 100644
--- a/api-router.go
+++ b/api-router.go
@@ -20,7 +20,7 @@ import router "github.com/gorilla/mux"
 
 // objectAPIHandler implements and provides http handlers for S3 API.
 type objectAPIHandlers struct {
-	ObjectAPI objectAPI
+	ObjectAPI ObjectLayer
 }
 
 // registerAPIRouter - registers S3 compatible APIs.
diff --git a/auth-handler.go b/auth-handler.go
index 3133615bc..cc602a26b 100644
--- a/auth-handler.go
+++ b/auth-handler.go
@@ -26,7 +26,6 @@ import (
 	"strings"
 
 	fastSha256 "github.com/minio/minio/pkg/crypto/sha256"
-	"github.com/minio/minio/pkg/probe"
 )
 
 // Verify if request has JWT.
@@ -113,12 +112,12 @@ func sumMD5(data []byte) []byte {
 // Verify if request has valid AWS Signature Version '4'.
 func isReqAuthenticated(r *http.Request) (s3Error APIErrorCode) {
 	if r == nil {
-		errorIf(probe.NewError(errInvalidArgument), "HTTP request cannot be empty.", nil)
+		errorIf(errInvalidArgument, "HTTP request cannot be empty.", nil)
 		return ErrInternalError
 	}
-	payload, e := ioutil.ReadAll(r.Body)
-	if e != nil {
-		errorIf(probe.NewError(e), "Unable to read HTTP body.", nil)
+	payload, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		errorIf(err, "Unable to read HTTP body.", nil)
 		return ErrInternalError
 	}
 	// Verify Content-Md5, if payload is set.
diff --git a/bucket-handlers.go b/bucket-handlers.go
index d0a9fbbc5..48d8b535c 100644
--- a/bucket-handlers.go
+++ b/bucket-handlers.go
@@ -29,7 +29,6 @@ import (
 	"strings"
 
 	mux "github.com/gorilla/mux"
-	"github.com/minio/minio/pkg/probe"
 )
 
 // http://docs.aws.amazon.com/AmazonS3/latest/dev/using-with-s3-actions.html
@@ -37,8 +36,8 @@ func enforceBucketPolicy(action string, bucket string, reqURL *url.URL) (s3Error
 	// Read saved bucket policy.
 	policy, err := readBucketPolicy(bucket)
 	if err != nil {
-		errorIf(err.Trace(bucket), "GetBucketPolicy failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "GetBucketPolicy failed.", nil)
+		switch err.(type) {
 		case BucketNotFound:
 			return ErrNoSuchBucket
 		case BucketNameInvalid:
@@ -49,9 +48,9 @@ func enforceBucketPolicy(action string, bucket string, reqURL *url.URL) (s3Error
 		}
 	}
 	// Parse the saved policy.
-	bucketPolicy, e := parseBucketPolicy(policy)
-	if e != nil {
-		errorIf(probe.NewError(e), "Parse policy failed.", nil)
+	bucketPolicy, err := parseBucketPolicy(policy)
+	if err != nil {
+		errorIf(err, "Parse policy failed.", nil)
 		return ErrAccessDenied
 	}
 
@@ -90,8 +89,8 @@ func (api objectAPIHandlers) GetBucketLocationHandler(w http.ResponseWriter, r *
 			return
 		}
 	case authTypeSigned, authTypePresigned:
-		payload, e := ioutil.ReadAll(r.Body)
-		if e != nil {
+		payload, err := ioutil.ReadAll(r.Body)
+		if err != nil {
 			writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 			return
 		}
@@ -117,10 +116,9 @@ func (api objectAPIHandlers) GetBucketLocationHandler(w http.ResponseWriter, r *
 		}
 	}
 
-	_, err := api.ObjectAPI.GetBucketInfo(bucket)
-	if err != nil {
-		errorIf(err.Trace(), "GetBucketInfo failed.", nil)
-		switch err.ToGoError().(type) {
+	if _, err := api.ObjectAPI.GetBucketInfo(bucket); err != nil {
+		errorIf(err, "GetBucketInfo failed.", nil)
+		switch err.(type) {
 		case BucketNotFound:
 			writeErrorResponse(w, r, ErrNoSuchBucket, r.URL.Path)
 		case BucketNameInvalid:
@@ -181,26 +179,24 @@ func (api objectAPIHandlers) ListMultipartUploadsHandler(w http.ResponseWriter,
 	}
 	if keyMarker != "" {
 		// Unescape keyMarker string
-		keyMarkerUnescaped, e := url.QueryUnescape(keyMarker)
-		if e != nil {
-			if e != nil {
-				// Return 'NoSuchKey' to indicate invalid marker key.
-				writeErrorResponse(w, r, ErrNoSuchKey, r.URL.Path)
-				return
-			}
-			keyMarker = keyMarkerUnescaped
-			// Marker not common with prefix is not implemented.
-			if !strings.HasPrefix(keyMarker, prefix) {
-				writeErrorResponse(w, r, ErrNotImplemented, r.URL.Path)
-				return
-			}
+		keyMarkerUnescaped, err := url.QueryUnescape(keyMarker)
+		if err != nil {
+			// Return 'NoSuchKey' to indicate invalid marker key.
+			writeErrorResponse(w, r, ErrNoSuchKey, r.URL.Path)
+			return
+		}
+		keyMarker = keyMarkerUnescaped
+		// Marker not common with prefix is not implemented.
+		if !strings.HasPrefix(keyMarker, prefix) {
+			writeErrorResponse(w, r, ErrNotImplemented, r.URL.Path)
+			return
 		}
 	}
 
 	listMultipartsInfo, err := api.ObjectAPI.ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads)
 	if err != nil {
-		errorIf(err.Trace(), "ListMultipartUploads failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "ListMultipartUploads failed.", nil)
+		switch err.(type) {
 		case BucketNotFound:
 			writeErrorResponse(w, r, ErrNoSuchBucket, r.URL.Path)
 		default:
@@ -259,8 +255,8 @@ func (api objectAPIHandlers) ListObjectsHandler(w http.ResponseWriter, r *http.R
 	// If marker is set unescape.
 	if marker != "" {
 		// Try to unescape marker.
-		markerUnescaped, e := url.QueryUnescape(marker)
-		if e != nil {
+		markerUnescaped, err := url.QueryUnescape(marker)
+		if err != nil {
 			// Return 'NoSuchKey' to indicate invalid marker key.
 			writeErrorResponse(w, r, ErrNoSuchKey, r.URL.Path)
 			return
@@ -284,7 +280,8 @@ func (api objectAPIHandlers) ListObjectsHandler(w http.ResponseWriter, r *http.R
 		writeSuccessResponse(w, encodedSuccessResponse)
 		return
 	}
-	switch err.ToGoError().(type) {
+	errorIf(err, "ListObjects failed.", nil)
+	switch err.(type) {
 	case BucketNameInvalid:
 		writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 	case BucketNotFound:
@@ -292,7 +289,6 @@ func (api objectAPIHandlers) ListObjectsHandler(w http.ResponseWriter, r *http.R
 	case ObjectNameInvalid:
 		writeErrorResponse(w, r, ErrNoSuchKey, r.URL.Path)
 	default:
-		errorIf(err.Trace(), "ListObjects failed.", nil)
 		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 	}
 }
@@ -347,8 +343,8 @@ func (api objectAPIHandlers) ListBucketsHandler(w http.ResponseWriter, r *http.R
 		writeSuccessResponse(w, encodedSuccessResponse)
 		return
 	}
-	errorIf(err.Trace(), "ListBuckets failed.", nil)
-	switch err.ToGoError().(type) {
+	errorIf(err, "ListBuckets failed.", nil)
+	switch err.(type) {
 	case StorageInsufficientReadResources:
 		writeErrorResponse(w, r, ErrInsufficientReadResources, r.URL.Path)
 	default:
@@ -398,16 +394,16 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 	deleteXMLBytes := make([]byte, r.ContentLength)
 
 	// Read incoming body XML bytes.
-	_, e := io.ReadFull(r.Body, deleteXMLBytes)
-	if e != nil {
-		errorIf(probe.NewError(e), "DeleteMultipleObjects failed.", nil)
+	if _, err := io.ReadFull(r.Body, deleteXMLBytes); err != nil {
+		errorIf(err, "DeleteMultipleObjects failed.", nil)
 		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 		return
 	}
 
 	// Unmarshal list of keys to be deleted.
 	deleteObjects := &DeleteObjectsRequest{}
-	if e := xml.Unmarshal(deleteXMLBytes, deleteObjects); e != nil {
+	if err := xml.Unmarshal(deleteXMLBytes, deleteObjects); err != nil {
+		errorIf(err, "DeleteMultipartObjects xml decoding failed.", nil)
 		writeErrorResponse(w, r, ErrMalformedXML, r.URL.Path)
 		return
 	}
@@ -422,8 +418,8 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 				ObjectName: object.ObjectName,
 			})
 		} else {
-			errorIf(err.Trace(object.ObjectName), "DeleteObject failed.", nil)
-			switch err.ToGoError().(type) {
+			errorIf(err, "DeleteObject failed.", nil)
+			switch err.(type) {
 			case BucketNameInvalid:
 				deleteErrors = append(deleteErrors, DeleteError{
 					Code:    errorCodeResponse[ErrInvalidBucketName].Code,
@@ -498,8 +494,8 @@ func (api objectAPIHandlers) PutBucketHandler(w http.ResponseWriter, r *http.Req
 	// Make bucket.
 	err := api.ObjectAPI.MakeBucket(bucket)
 	if err != nil {
-		errorIf(err.Trace(), "MakeBucket failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "MakeBucket failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketExists:
@@ -514,24 +510,25 @@ func (api objectAPIHandlers) PutBucketHandler(w http.ResponseWriter, r *http.Req
 	writeSuccessResponse(w, nil)
 }
 
-func extractHTTPFormValues(reader *multipart.Reader) (io.Reader, map[string]string, *probe.Error) {
+func extractHTTPFormValues(reader *multipart.Reader) (io.Reader, map[string]string, error) {
 	/// HTML Form values
 	formValues := make(map[string]string)
 	filePart := new(bytes.Buffer)
-	var e error
-	for e == nil {
+	var err error
+	for err == nil {
 		var part *multipart.Part
-		part, e = reader.NextPart()
+		part, err = reader.NextPart()
 		if part != nil {
 			if part.FileName() == "" {
-				buffer, e := ioutil.ReadAll(part)
-				if e != nil {
-					return nil, nil, probe.NewError(e)
+				var buffer []byte
+				buffer, err = ioutil.ReadAll(part)
+				if err != nil {
+					return nil, nil, err
 				}
 				formValues[http.CanonicalHeaderKey(part.FormName())] = string(buffer)
 			} else {
-				if _, e := io.Copy(filePart, part); e != nil {
-					return nil, nil, probe.NewError(e)
+				if _, err = io.Copy(filePart, part); err != nil {
+					return nil, nil, err
 				}
 			}
 		}
@@ -546,16 +543,16 @@ func extractHTTPFormValues(reader *multipart.Reader) (io.Reader, map[string]stri
 func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *http.Request) {
 	// Here the parameter is the size of the form data that should
 	// be loaded in memory, the remaining being put in temporary files.
-	reader, e := r.MultipartReader()
-	if e != nil {
-		errorIf(probe.NewError(e), "Unable to initialize multipart reader.", nil)
+	reader, err := r.MultipartReader()
+	if err != nil {
+		errorIf(err, "Unable to initialize multipart reader.", nil)
 		writeErrorResponse(w, r, ErrMalformedPOSTRequest, r.URL.Path)
 		return
 	}
 
 	fileBody, formValues, err := extractHTTPFormValues(reader)
 	if err != nil {
-		errorIf(err.Trace(), "Unable to parse form values.", nil)
+		errorIf(err, "Unable to parse form values.", nil)
 		writeErrorResponse(w, r, ErrMalformedPOSTRequest, r.URL.Path)
 		return
 	}
@@ -575,8 +572,8 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 	}
 	md5Sum, err := api.ObjectAPI.PutObject(bucket, object, -1, fileBody, nil)
 	if err != nil {
-		errorIf(err.Trace(), "PutObject failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "PutObject failed.", nil)
+		switch err.(type) {
 		case StorageFull:
 			writeErrorResponse(w, r, ErrStorageFull, r.URL.Path)
 		case BucketNotFound:
@@ -626,10 +623,9 @@ func (api objectAPIHandlers) HeadBucketHandler(w http.ResponseWriter, r *http.Re
 		}
 	}
 
-	_, err := api.ObjectAPI.GetBucketInfo(bucket)
-	if err != nil {
-		errorIf(err.Trace(), "GetBucketInfo failed.", nil)
-		switch err.ToGoError().(type) {
+	if _, err := api.ObjectAPI.GetBucketInfo(bucket); err != nil {
+		errorIf(err, "GetBucketInfo failed.", nil)
+		switch err.(type) {
 		case BucketNotFound:
 			writeErrorResponse(w, r, ErrNoSuchBucket, r.URL.Path)
 		case BucketNameInvalid:
@@ -661,10 +657,9 @@ func (api objectAPIHandlers) DeleteBucketHandler(w http.ResponseWriter, r *http.
 		}
 	}
 
-	err := api.ObjectAPI.DeleteBucket(bucket)
-	if err != nil {
-		errorIf(err.Trace(), "DeleteBucket failed.", nil)
-		switch err.ToGoError().(type) {
+	if err := api.ObjectAPI.DeleteBucket(bucket); err != nil {
+		errorIf(err, "DeleteBucket failed.", nil)
+		switch err.(type) {
 		case BucketNotFound:
 			writeErrorResponse(w, r, ErrNoSuchBucket, r.URL.Path)
 		case BucketNotEmpty:
diff --git a/bucket-policy-handlers.go b/bucket-policy-handlers.go
index 35f674d81..cd9302f06 100644
--- a/bucket-policy-handlers.go
+++ b/bucket-policy-handlers.go
@@ -25,7 +25,6 @@ import (
 	"strings"
 
 	mux "github.com/gorilla/mux"
-	"github.com/minio/minio/pkg/probe"
 )
 
 // maximum supported access policy size.
@@ -67,8 +66,8 @@ func bucketPolicyMatchStatement(action string, resource string, conditions map[s
 func bucketPolicyActionMatch(action string, statement policyStatement) bool {
 	for _, policyAction := range statement.Actions {
 		// Policy action can be a regex, validate the action with matching string.
-		matched, e := regexp.MatchString(policyAction, action)
-		fatalIf(probe.NewError(e), "Invalid pattern, please verify the pattern string.", nil)
+		matched, err := regexp.MatchString(policyAction, action)
+		fatalIf(err, "Invalid pattern, please verify the pattern string.", nil)
 		if matched {
 			return true
 		}
@@ -79,8 +78,8 @@ func bucketPolicyActionMatch(action string, statement policyStatement) bool {
 // Verify if given resource matches with policy statement.
 func bucketPolicyResourceMatch(resource string, statement policyStatement) bool {
 	for _, presource := range statement.Resources {
-		matched, e := regexp.MatchString(presource, strings.TrimPrefix(resource, "/"))
-		fatalIf(probe.NewError(e), "Invalid pattern, please verify the pattern string.", nil)
+		matched, err := regexp.MatchString(presource, strings.TrimPrefix(resource, "/"))
+		fatalIf(err, "Invalid pattern, please verify the pattern string.", nil)
 		// For any path matches, we return quickly and the let the caller continue.
 		if matched {
 			return true
@@ -161,17 +160,17 @@ func (api objectAPIHandlers) PutBucketPolicyHandler(w http.ResponseWriter, r *ht
 	// Read access policy up to maxAccessPolicySize.
 	// http://docs.aws.amazon.com/AmazonS3/latest/dev/access-policy-language-overview.html
 	// bucket policies are limited to 20KB in size, using a limit reader.
-	bucketPolicyBuf, e := ioutil.ReadAll(io.LimitReader(r.Body, maxAccessPolicySize))
-	if e != nil {
-		errorIf(probe.NewError(e).Trace(bucket), "Reading policy failed.", nil)
+	bucketPolicyBuf, err := ioutil.ReadAll(io.LimitReader(r.Body, maxAccessPolicySize))
+	if err != nil {
+		errorIf(err, "Reading policy failed.", nil)
 		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 		return
 	}
 
 	// Parse bucket policy.
-	bucketPolicy, e := parseBucketPolicy(bucketPolicyBuf)
-	if e != nil {
-		errorIf(probe.NewError(e), "Unable to parse bucket policy.", nil)
+	bucketPolicy, err := parseBucketPolicy(bucketPolicyBuf)
+	if err != nil {
+		errorIf(err, "Unable to parse bucket policy.", nil)
 		writeErrorResponse(w, r, ErrInvalidPolicyDocument, r.URL.Path)
 		return
 	}
@@ -183,10 +182,9 @@ func (api objectAPIHandlers) PutBucketPolicyHandler(w http.ResponseWriter, r *ht
 	}
 
 	// Save bucket policy.
-	err := writeBucketPolicy(bucket, bucketPolicyBuf)
-	if err != nil {
-		errorIf(err.Trace(bucket, string(bucketPolicyBuf)), "SaveBucketPolicy failed.", nil)
-		switch err.ToGoError().(type) {
+	if err := writeBucketPolicy(bucket, bucketPolicyBuf); err != nil {
+		errorIf(err, "SaveBucketPolicy failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		default:
@@ -218,10 +216,9 @@ func (api objectAPIHandlers) DeleteBucketPolicyHandler(w http.ResponseWriter, r
 	}
 
 	// Delete bucket access policy.
-	err := removeBucketPolicy(bucket)
-	if err != nil {
-		errorIf(err.Trace(bucket), "DeleteBucketPolicy failed.", nil)
-		switch err.ToGoError().(type) {
+	if err := removeBucketPolicy(bucket); err != nil {
+		errorIf(err, "DeleteBucketPolicy failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketPolicyNotFound:
@@ -257,8 +254,8 @@ func (api objectAPIHandlers) GetBucketPolicyHandler(w http.ResponseWriter, r *ht
 	// Read bucket access policy.
 	p, err := readBucketPolicy(bucket)
 	if err != nil {
-		errorIf(err.Trace(bucket), "GetBucketPolicy failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "GetBucketPolicy failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketPolicyNotFound:
diff --git a/bucket-policy.go b/bucket-policy.go
index 3791321a8..d9186878b 100644
--- a/bucket-policy.go
+++ b/bucket-policy.go
@@ -20,132 +20,115 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-
-	"github.com/minio/minio/pkg/probe"
 )
 
 // getBucketsConfigPath - get buckets path.
-func getBucketsConfigPath() (string, *probe.Error) {
+func getBucketsConfigPath() (string, error) {
 	configPath, err := getConfigPath()
 	if err != nil {
-		return "", err.Trace()
+		return "", err
 	}
 	return filepath.Join(configPath, "buckets"), nil
 }
 
 // createBucketsConfigPath - create buckets directory.
-func createBucketsConfigPath() *probe.Error {
+func createBucketsConfigPath() error {
 	bucketsConfigPath, err := getBucketsConfigPath()
 	if err != nil {
 		return err
 	}
-	if e := os.MkdirAll(bucketsConfigPath, 0700); e != nil {
-		return probe.NewError(e)
-	}
-	return nil
+	return os.MkdirAll(bucketsConfigPath, 0700)
 }
 
 // getBucketConfigPath - get bucket config path.
-func getBucketConfigPath(bucket string) (string, *probe.Error) {
+func getBucketConfigPath(bucket string) (string, error) {
 	bucketsConfigPath, err := getBucketsConfigPath()
 	if err != nil {
-		return "", err.Trace()
+		return "", err
 	}
 	return filepath.Join(bucketsConfigPath, bucket), nil
 }
 
 // createBucketConfigPath - create bucket config directory.
-func createBucketConfigPath(bucket string) *probe.Error {
+func createBucketConfigPath(bucket string) error {
 	bucketConfigPath, err := getBucketConfigPath(bucket)
 	if err != nil {
 		return err
 	}
-	if e := os.MkdirAll(bucketConfigPath, 0700); e != nil {
-		return probe.NewError(e)
-	}
-	return nil
+	return os.MkdirAll(bucketConfigPath, 0700)
 }
 
 // readBucketPolicy - read bucket policy.
-func readBucketPolicy(bucket string) ([]byte, *probe.Error) {
+func readBucketPolicy(bucket string) ([]byte, error) {
 	// Verify bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return nil, probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return nil, BucketNameInvalid{Bucket: bucket}
 	}
 
 	bucketConfigPath, err := getBucketConfigPath(bucket)
 	if err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 
 	// Get policy file.
 	bucketPolicyFile := filepath.Join(bucketConfigPath, "access-policy.json")
-	if _, e := os.Stat(bucketPolicyFile); e != nil {
-		if os.IsNotExist(e) {
-			return nil, probe.NewError(BucketPolicyNotFound{Bucket: bucket})
+	if _, err = os.Stat(bucketPolicyFile); err != nil {
+		if os.IsNotExist(err) {
+			return nil, BucketPolicyNotFound{Bucket: bucket}
 		}
-		return nil, probe.NewError(e)
+		return nil, err
 	}
-
-	accessPolicyBytes, e := ioutil.ReadFile(bucketPolicyFile)
-	if e != nil {
-		return nil, probe.NewError(e)
-	}
-	return accessPolicyBytes, nil
+	return ioutil.ReadFile(bucketPolicyFile)
 }
 
 // removeBucketPolicy - remove bucket policy.
-func removeBucketPolicy(bucket string) *probe.Error {
+func removeBucketPolicy(bucket string) error {
 	// Verify bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return BucketNameInvalid{Bucket: bucket}
 	}
 
 	bucketConfigPath, err := getBucketConfigPath(bucket)
 	if err != nil {
-		return err.Trace(bucket)
+		return err
 	}
 
 	// Get policy file.
 	bucketPolicyFile := filepath.Join(bucketConfigPath, "access-policy.json")
-	if _, e := os.Stat(bucketPolicyFile); e != nil {
-		if os.IsNotExist(e) {
-			return probe.NewError(BucketPolicyNotFound{Bucket: bucket})
+	if _, err = os.Stat(bucketPolicyFile); err != nil {
+		if os.IsNotExist(err) {
+			return BucketPolicyNotFound{Bucket: bucket}
 		}
-		return probe.NewError(e)
+		return err
 	}
 	return nil
 }
 
 // writeBucketPolicy - save bucket policy.
-func writeBucketPolicy(bucket string, accessPolicyBytes []byte) *probe.Error {
+func writeBucketPolicy(bucket string, accessPolicyBytes []byte) error {
 	// Verify if bucket path legal
 	if !IsValidBucketName(bucket) {
-		return probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return BucketNameInvalid{Bucket: bucket}
 	}
 
 	// Create bucket config path.
 	if err := createBucketConfigPath(bucket); err != nil {
-		return err.Trace()
+		return err
 	}
 
 	bucketConfigPath, err := getBucketConfigPath(bucket)
 	if err != nil {
-		return err.Trace()
+		return err
 	}
 
 	// Get policy file.
 	bucketPolicyFile := filepath.Join(bucketConfigPath, "access-policy.json")
-	if _, e := os.Stat(bucketPolicyFile); e != nil {
-		if !os.IsNotExist(e) {
-			return probe.NewError(e)
+	if _, err := os.Stat(bucketPolicyFile); err != nil {
+		if !os.IsNotExist(err) {
+			return err
 		}
 	}
 
 	// Write bucket policy.
-	if e := ioutil.WriteFile(bucketPolicyFile, accessPolicyBytes, 0600); e != nil {
-		return probe.NewError(e)
-	}
-
-	return nil
+	return ioutil.WriteFile(bucketPolicyFile, accessPolicyBytes, 0600)
 }
diff --git a/certs.go b/certs.go
index 90fb5885b..9897dfd9d 100644
--- a/certs.go
+++ b/certs.go
@@ -21,26 +21,22 @@ import (
 	"path/filepath"
 
 	"github.com/minio/go-homedir"
-	"github.com/minio/minio/pkg/probe"
 )
 
 // createCertsPath create certs path.
-func createCertsPath() *probe.Error {
+func createCertsPath() error {
 	certsPath, err := getCertsPath()
 	if err != nil {
-		return err.Trace()
+		return err
 	}
-	if err := os.MkdirAll(certsPath, 0700); err != nil {
-		return probe.NewError(err)
-	}
-	return nil
+	return os.MkdirAll(certsPath, 0700)
 }
 
 // getCertsPath get certs path.
-func getCertsPath() (string, *probe.Error) {
-	homeDir, e := homedir.Dir()
-	if e != nil {
-		return "", probe.NewError(e)
+func getCertsPath() (string, error) {
+	homeDir, err := homedir.Dir()
+	if err != nil {
+		return "", err
 	}
 	certsPath := filepath.Join(homeDir, globalMinioCertsDir)
 	return certsPath, nil
@@ -49,7 +45,7 @@ func getCertsPath() (string, *probe.Error) {
 // mustGetCertsPath must get certs path.
 func mustGetCertsPath() string {
 	certsPath, err := getCertsPath()
-	fatalIf(err.Trace(), "Unable to retrieve certs path.", nil)
+	fatalIf(err, "Unable to retrieve certs path.", nil)
 	return certsPath
 }
 
diff --git a/config-migrate.go b/config-migrate.go
index e198c0f17..b0b92f50e 100644
--- a/config-migrate.go
+++ b/config-migrate.go
@@ -22,7 +22,6 @@ import (
 	"path/filepath"
 
 	"github.com/minio/mc/pkg/console"
-	"github.com/minio/minio/pkg/probe"
 	"github.com/minio/minio/pkg/quick"
 )
 
@@ -38,35 +37,31 @@ func migrateConfig() {
 // Version '1' is not supported anymore and deprecated, safe to delete.
 func purgeV1() {
 	cv1, err := loadConfigV1()
-	if err != nil {
-		if os.IsNotExist(err.ToGoError()) {
-			return
-		}
+	if err != nil && os.IsNotExist(err) {
+		return
 	}
-	fatalIf(err.Trace(), "Unable to load config version ‘1’.", nil)
+	fatalIf(err, "Unable to load config version ‘1’.", nil)
 
 	if cv1.Version == "1" {
 		console.Println("Unsupported config version ‘1’ found, removed successfully.")
 		/// Purge old fsUsers.json file
 		configPath, err := getConfigPath()
-		fatalIf(err.Trace(), "Unable to retrieve config path.", nil)
+		fatalIf(err, "Unable to retrieve config path.", nil)
 
 		configFile := filepath.Join(configPath, "fsUsers.json")
 		os.RemoveAll(configFile)
 	}
-	fatalIf(probe.NewError(errors.New("")), "Unexpected version found ‘"+cv1.Version+"’, cannot migrate.", nil)
+	fatalIf(errors.New(""), "Unexpected version found ‘"+cv1.Version+"’, cannot migrate.", nil)
 }
 
 // Version '2' to '3' config migration adds new fields and re-orders
 // previous fields. Simplifies config for future additions.
 func migrateV2ToV3() {
 	cv2, err := loadConfigV2()
-	if err != nil {
-		if os.IsNotExist(err.ToGoError()) {
-			return
-		}
+	if err != nil && os.IsNotExist(err) {
+		return
 	}
-	fatalIf(err.Trace(), "Unable to load config version ‘2’.", nil)
+	fatalIf(err, "Unable to load config version ‘2’.", nil)
 	if cv2.Version != "2" {
 		return
 	}
@@ -99,14 +94,14 @@ func migrateV2ToV3() {
 	srvConfig.Logger.Syslog = slogger
 
 	qc, err := quick.New(srvConfig)
-	fatalIf(err.Trace(), "Unable to initialize config.", nil)
+	fatalIf(err, "Unable to initialize config.", nil)
 
 	configFile, err := getConfigFile()
-	fatalIf(err.Trace(), "Unable to get config file.", nil)
+	fatalIf(err, "Unable to get config file.", nil)
 
 	// Migrate the config.
 	err = qc.Save(configFile)
-	fatalIf(err.Trace(), "Migrating from version ‘"+cv2.Version+"’ to ‘"+srvConfig.Version+"’ failed.", nil)
+	fatalIf(err, "Migrating from version ‘"+cv2.Version+"’ to ‘"+srvConfig.Version+"’ failed.", nil)
 
 	console.Println("Migration from version ‘" + cv2.Version + "’ to ‘" + srvConfig.Version + "’ completed successfully.")
 }
@@ -116,12 +111,10 @@ func migrateV2ToV3() {
 // the config for future additions.
 func migrateV3ToV4() {
 	cv3, err := loadConfigV3()
-	if err != nil {
-		if os.IsNotExist(err.ToGoError()) {
-			return
-		}
+	if err != nil && os.IsNotExist(err) {
+		return
 	}
-	fatalIf(err.Trace(), "Unable to load config version ‘3’.", nil)
+	fatalIf(err, "Unable to load config version ‘3’.", nil)
 	if cv3.Version != "3" {
 		return
 	}
@@ -136,12 +129,12 @@ func migrateV3ToV4() {
 	srvConfig.Logger.Syslog = cv3.Logger.Syslog
 
 	qc, err := quick.New(srvConfig)
-	fatalIf(err.Trace(), "Unable to initialize the quick config.", nil)
+	fatalIf(err, "Unable to initialize the quick config.", nil)
 	configFile, err := getConfigFile()
-	fatalIf(err.Trace(), "Unable to get config file.", nil)
+	fatalIf(err, "Unable to get config file.", nil)
 
 	err = qc.Save(configFile)
-	fatalIf(err.Trace(), "Migrating from version ‘"+cv3.Version+"’ to ‘"+srvConfig.Version+"’ failed.", nil)
+	fatalIf(err, "Migrating from version ‘"+cv3.Version+"’ to ‘"+srvConfig.Version+"’ failed.", nil)
 
 	console.Println("Migration from version ‘" + cv3.Version + "’ to ‘" + srvConfig.Version + "’ completed successfully.")
 }
diff --git a/config-old.go b/config-old.go
index ca0157eb2..be618e98c 100644
--- a/config-old.go
+++ b/config-old.go
@@ -4,7 +4,6 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/minio/minio/pkg/probe"
 	"github.com/minio/minio/pkg/quick"
 )
 
@@ -16,23 +15,23 @@ type configV1 struct {
 }
 
 // loadConfigV1 load config
-func loadConfigV1() (*configV1, *probe.Error) {
+func loadConfigV1() (*configV1, error) {
 	configPath, err := getConfigPath()
 	if err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 	configFile := filepath.Join(configPath, "fsUsers.json")
-	if _, err := os.Stat(configFile); err != nil {
-		return nil, probe.NewError(err)
+	if _, err = os.Stat(configFile); err != nil {
+		return nil, err
 	}
 	a := &configV1{}
 	a.Version = "1"
 	qc, err := quick.New(a)
 	if err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 	if err := qc.Load(configFile); err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 	return qc.Data().(*configV1), nil
 }
@@ -60,22 +59,22 @@ type configV2 struct {
 }
 
 // loadConfigV2 load config version '2'.
-func loadConfigV2() (*configV2, *probe.Error) {
+func loadConfigV2() (*configV2, error) {
 	configFile, err := getConfigFile()
 	if err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
-	if _, err := os.Stat(configFile); err != nil {
-		return nil, probe.NewError(err)
+	if _, err = os.Stat(configFile); err != nil {
+		return nil, err
 	}
 	a := &configV2{}
 	a.Version = "2"
 	qc, err := quick.New(a)
 	if err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 	if err := qc.Load(configFile); err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 	return qc.Data().(*configV2), nil
 }
@@ -127,22 +126,22 @@ type configV3 struct {
 }
 
 // loadConfigV3 load config version '3'.
-func loadConfigV3() (*configV3, *probe.Error) {
+func loadConfigV3() (*configV3, error) {
 	configFile, err := getConfigFile()
 	if err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
-	if _, err := os.Stat(configFile); err != nil {
-		return nil, probe.NewError(err)
+	if _, err = os.Stat(configFile); err != nil {
+		return nil, err
 	}
 	a := &configV3{}
 	a.Version = "3"
 	qc, err := quick.New(a)
 	if err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 	if err := qc.Load(configFile); err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 	return qc.Data().(*configV3), nil
 }
diff --git a/config-v4.go b/config-v4.go
index 8a6254259..1985a1227 100644
--- a/config-v4.go
+++ b/config-v4.go
@@ -20,7 +20,6 @@ import (
 	"os"
 	"sync"
 
-	"github.com/minio/minio/pkg/probe"
 	"github.com/minio/minio/pkg/quick"
 )
 
@@ -40,7 +39,7 @@ type serverConfigV4 struct {
 }
 
 // initConfig - initialize server config. config version (called only once).
-func initConfig() *probe.Error {
+func initConfig() error {
 	if !isConfigFileExists() {
 		srvCfg := &serverConfigV4{}
 		srvCfg.Version = globalMinioConfigVersion
@@ -55,41 +54,37 @@ func initConfig() *probe.Error {
 		// Create config path.
 		err := createConfigPath()
 		if err != nil {
-			return err.Trace()
+			return err
 		}
 
 		// Create certs path.
 		err = createCertsPath()
 		if err != nil {
-			return err.Trace()
+			return err
 		}
 
 		// Save the new config globally.
 		serverConfig = srvCfg
 
 		// Save config into file.
-		err = serverConfig.Save()
-		if err != nil {
-			return err.Trace()
-		}
-		return nil
+		return serverConfig.Save()
 	}
 	configFile, err := getConfigFile()
 	if err != nil {
-		return err.Trace()
+		return err
 	}
-	if _, e := os.Stat(configFile); err != nil {
-		return probe.NewError(e)
+	if _, err = os.Stat(configFile); err != nil {
+		return err
 	}
 	srvCfg := &serverConfigV4{}
 	srvCfg.Version = globalMinioConfigVersion
 	srvCfg.rwMutex = &sync.RWMutex{}
 	qc, err := quick.New(srvCfg)
 	if err != nil {
-		return err.Trace()
+		return err
 	}
 	if err := qc.Load(configFile); err != nil {
-		return err.Trace()
+		return err
 	}
 	// Save the loaded config globally.
 	serverConfig = qc.Data().(*serverConfigV4)
@@ -181,27 +176,22 @@ func (s serverConfigV4) GetCredential() credential {
 }
 
 // Save config.
-func (s serverConfigV4) Save() *probe.Error {
+func (s serverConfigV4) Save() error {
 	s.rwMutex.RLock()
 	defer s.rwMutex.RUnlock()
 
 	// get config file.
 	configFile, err := getConfigFile()
 	if err != nil {
-		return err.Trace()
+		return err
 	}
 
 	// initialize quick.
 	qc, err := quick.New(&s)
 	if err != nil {
-		return err.Trace()
+		return err
 	}
 
 	// Save config file.
-	if err := qc.Save(configFile); err != nil {
-		return err.Trace()
-	}
-
-	// Return success.
-	return nil
+	return qc.Save(configFile)
 }
diff --git a/config.go b/config.go
index 83439cbdc..be7203d36 100644
--- a/config.go
+++ b/config.go
@@ -21,7 +21,6 @@ import (
 	"path/filepath"
 
 	"github.com/minio/go-homedir"
-	"github.com/minio/minio/pkg/probe"
 )
 
 // configPath for custom config path only for testing purposes
@@ -33,13 +32,13 @@ func setGlobalConfigPath(configPath string) {
 }
 
 // getConfigPath get server config path
-func getConfigPath() (string, *probe.Error) {
+func getConfigPath() (string, error) {
 	if customConfigPath != "" {
 		return customConfigPath, nil
 	}
-	homeDir, e := homedir.Dir()
-	if e != nil {
-		return "", probe.NewError(e)
+	homeDir, err := homedir.Dir()
+	if err != nil {
+		return "", err
 	}
 	configPath := filepath.Join(homeDir, globalMinioConfigDir)
 	return configPath, nil
@@ -48,27 +47,24 @@ func getConfigPath() (string, *probe.Error) {
 // mustGetConfigPath must get server config path.
 func mustGetConfigPath() string {
 	configPath, err := getConfigPath()
-	fatalIf(err.Trace(), "Unable to get config path.", nil)
+	fatalIf(err, "Unable to get config path.", nil)
 	return configPath
 }
 
 // createConfigPath create server config path.
-func createConfigPath() *probe.Error {
+func createConfigPath() error {
 	configPath, err := getConfigPath()
 	if err != nil {
-		return err.Trace()
+		return err
 	}
-	if err := os.MkdirAll(configPath, 0700); err != nil {
-		return probe.NewError(err)
-	}
-	return nil
+	return os.MkdirAll(configPath, 0700)
 }
 
 // isConfigFileExists - returns true if config file exists.
 func isConfigFileExists() bool {
-	st, e := os.Stat(mustGetConfigFile())
+	st, err := os.Stat(mustGetConfigFile())
 	// If file exists and is regular return true.
-	if e == nil && st.Mode().IsRegular() {
+	if err == nil && st.Mode().IsRegular() {
 		return true
 	}
 	return false
@@ -77,16 +73,16 @@ func isConfigFileExists() bool {
 // mustGetConfigFile must get server config file.
 func mustGetConfigFile() string {
 	configFile, err := getConfigFile()
-	fatalIf(err.Trace(), "Unable to get config file.", nil)
+	fatalIf(err, "Unable to get config file.", nil)
 
 	return configFile
 }
 
 // getConfigFile get server config file.
-func getConfigFile() (string, *probe.Error) {
+func getConfigFile() (string, error) {
 	configPath, err := getConfigPath()
 	if err != nil {
-		return "", err.Trace()
+		return "", err
 	}
 	return filepath.Join(configPath, globalMinioConfigFile), nil
 }
diff --git a/object-api-multipart.go b/fs-objects-multipart.go
similarity index 55%
rename from object-api-multipart.go
rename to fs-objects-multipart.go
index 860c2fa74..a341cc4d5 100644
--- a/object-api-multipart.go
+++ b/fs-objects-multipart.go
@@ -27,28 +27,22 @@ import (
 	"strings"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/minio/minio/pkg/probe"
 	"github.com/skyrings/skyring-common/tools/uuid"
 )
 
-const (
-	// Minio meta volume.
-	minioMetaVolume = ".minio"
-)
-
 // listLeafEntries - lists all entries if a given prefixPath is a leaf
 // directory, returns error if any - returns empty list if prefixPath
 // is not a leaf directory.
-func (o objectAPI) listLeafEntries(prefixPath string) (entries []FileInfo, e error) {
+func (fs fsObjects) listLeafEntries(prefixPath string) (entries []FileInfo, e error) {
 	var markerPath string
 	for {
-		fileInfos, eof, e := o.storage.ListFiles(minioMetaVolume, prefixPath, markerPath, false, 1000)
-		if e != nil {
+		fileInfos, eof, err := fs.storage.ListFiles(minioMetaVolume, prefixPath, markerPath, false, 1000)
+		if err != nil {
 			log.WithFields(logrus.Fields{
 				"prefixPath": prefixPath,
 				"markerPath": markerPath,
-			}).Errorf("%s", e)
-			return nil, e
+			}).Errorf("%s", err)
+			return nil, err
 		}
 		for _, fileInfo := range fileInfos {
 			// Set marker for next batch of ListFiles.
@@ -72,7 +66,7 @@ func (o objectAPI) listLeafEntries(prefixPath string) (entries []FileInfo, e err
 }
 
 // listMetaVolumeFiles - list all files at a given prefix inside minioMetaVolume.
-func (o objectAPI) listMetaVolumeFiles(prefixPath string, markerPath string, recursive bool, maxKeys int) (allFileInfos []FileInfo, eof bool, e error) {
+func (fs fsObjects) listMetaVolumeFiles(prefixPath string, markerPath string, recursive bool, maxKeys int) (allFileInfos []FileInfo, eof bool, err error) {
 	// newMaxKeys tracks the size of entries which are going to be
 	// returned back.
 	var newMaxKeys int
@@ -82,15 +76,15 @@ func (o objectAPI) listMetaVolumeFiles(prefixPath string, markerPath string, rec
 	for {
 		var fileInfos []FileInfo
 		// List files up to maxKeys-newMaxKeys, since we are skipping entries for special files.
-		fileInfos, eof, e = o.storage.ListFiles(minioMetaVolume, prefixPath, markerPath, recursive, maxKeys-newMaxKeys)
-		if e != nil {
+		fileInfos, eof, err = fs.storage.ListFiles(minioMetaVolume, prefixPath, markerPath, recursive, maxKeys-newMaxKeys)
+		if err != nil {
 			log.WithFields(logrus.Fields{
 				"prefixPath": prefixPath,
 				"markerPath": markerPath,
 				"recursive":  recursive,
 				"maxKeys":    maxKeys,
-			}).Errorf("%s", e)
-			return nil, true, e
+			}).Errorf("%s", err)
+			return nil, true, err
 		}
 		// Loop through and validate individual file.
 		for _, fi := range fileInfos {
@@ -99,20 +93,18 @@ func (o objectAPI) listMetaVolumeFiles(prefixPath string, markerPath string, rec
 				// List all the entries if fi.Name is a leaf directory, if
 				// fi.Name is not a leaf directory then the resulting
 				// entries are empty.
-				entries, e = o.listLeafEntries(fi.Name)
-				if e != nil {
+				entries, err = fs.listLeafEntries(fi.Name)
+				if err != nil {
 					log.WithFields(logrus.Fields{
 						"prefixPath": fi.Name,
-					}).Errorf("%s", e)
-					return nil, false, e
+					}).Errorf("%s", err)
+					return nil, false, err
 				}
 			}
 			// Set markerPath for next batch of listing.
 			markerPath = fi.Name
 			if len(entries) > 0 {
-
 				// We reach here for non-recursive case and a leaf entry.
-
 				for _, entry := range entries {
 					allFileInfos = append(allFileInfos, entry)
 					newMaxKeys++
@@ -121,24 +113,22 @@ func (o objectAPI) listMetaVolumeFiles(prefixPath string, markerPath string, rec
 					if newMaxKeys == maxKeys {
 						// Return values:
 						// allFileInfos : "maxKeys" number of entries.
-						// eof : eof returned by o.storage.ListFiles()
+						// eof : eof returned by fs.storage.ListFiles()
 						// error : nil
 						return
 					}
 				}
-				continue
-			}
-
-			// We reach here for a non-recursive case non-leaf entry
-			// OR recursive case with fi.Name matching pattern bucket/object/uploadID[.partNum.md5sum]
-
-			if !fi.Mode.IsDir() { // Do not skip non-recursive case directory entries.
-				// Skip files matching pattern bucket/object/uploadID.partNum.md5sum
-				// and retain files matching pattern bucket/object/uploadID
-				specialFile := path.Base(fi.Name)
-				if strings.Contains(specialFile, ".") {
-					// Contains partnumber and md5sum info, skip this.
-					continue
+			} else {
+				// We reach here for a non-recursive case non-leaf entry
+				// OR recursive case with fi.Name matching pattern bucket/object/uploadID[.partNum.md5sum]
+				if !fi.Mode.IsDir() { // Do not skip non-recursive case directory entries.
+					// Skip files matching pattern bucket/object/uploadID.partNum.md5sum
+					// and retain files matching pattern bucket/object/uploadID
+					specialFile := path.Base(fi.Name)
+					if strings.Contains(specialFile, ".") {
+						// Contains partnumber and md5sum info, skip this.
+						continue
+					}
 				}
 			}
 			allFileInfos = append(allFileInfos, fi)
@@ -148,7 +138,7 @@ func (o objectAPI) listMetaVolumeFiles(prefixPath string, markerPath string, rec
 			if newMaxKeys == maxKeys {
 				// Return values:
 				// allFileInfos : "maxKeys" number of entries.
-				// eof : eof returned by o.storage.ListFiles()
+				// eof : eof returned by fs.storage.ListFiles()
 				// error : nil
 				return
 			}
@@ -164,41 +154,41 @@ func (o objectAPI) listMetaVolumeFiles(prefixPath string, markerPath string, rec
 }
 
 // ListMultipartUploads - list multipart uploads.
-func (o objectAPI) ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarker, delimiter string, maxUploads int) (ListMultipartsInfo, *probe.Error) {
+func (fs fsObjects) ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarker, delimiter string, maxUploads int) (ListMultipartsInfo, error) {
 	result := ListMultipartsInfo{}
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return ListMultipartsInfo{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return ListMultipartsInfo{}, (BucketNameInvalid{Bucket: bucket})
 	}
 	if !IsValidObjectPrefix(prefix) {
-		return ListMultipartsInfo{}, probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: prefix})
+		return ListMultipartsInfo{}, (ObjectNameInvalid{Bucket: bucket, Object: prefix})
 	}
 	// Verify if delimiter is anything other than '/', which we do not support.
 	if delimiter != "" && delimiter != slashSeparator {
-		return ListMultipartsInfo{}, probe.NewError(UnsupportedDelimiter{
+		return ListMultipartsInfo{}, (UnsupportedDelimiter{
 			Delimiter: delimiter,
 		})
 	}
 	// Verify if marker has prefix.
 	if keyMarker != "" && !strings.HasPrefix(keyMarker, prefix) {
-		return ListMultipartsInfo{}, probe.NewError(InvalidMarkerPrefixCombination{
+		return ListMultipartsInfo{}, (InvalidMarkerPrefixCombination{
 			Marker: keyMarker,
 			Prefix: prefix,
 		})
 	}
 	if uploadIDMarker != "" {
 		if strings.HasSuffix(keyMarker, slashSeparator) {
-			return result, probe.NewError(InvalidUploadIDKeyCombination{
+			return result, (InvalidUploadIDKeyCombination{
 				UploadIDMarker: uploadIDMarker,
 				KeyMarker:      keyMarker,
 			})
 		}
-		id, e := uuid.Parse(uploadIDMarker)
-		if e != nil {
-			return result, probe.NewError(e)
+		id, err := uuid.Parse(uploadIDMarker)
+		if err != nil {
+			return result, err
 		}
 		if id.IsZero() {
-			return result, probe.NewError(MalformedUploadID{
+			return result, (MalformedUploadID{
 				UploadID: uploadIDMarker,
 			})
 		}
@@ -220,15 +210,15 @@ func (o objectAPI) ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarke
 		keyMarkerPath = pathJoin(pathJoin(bucket, keyMarker), uploadIDMarker)
 	}
 	// List all the multipart files at prefixPath, starting with marker keyMarkerPath.
-	fileInfos, eof, e := o.listMetaVolumeFiles(prefixPath, keyMarkerPath, recursive, maxUploads)
-	if e != nil {
+	fileInfos, eof, err := fs.listMetaVolumeFiles(prefixPath, keyMarkerPath, recursive, maxUploads)
+	if err != nil {
 		log.WithFields(logrus.Fields{
 			"prefixPath": prefixPath,
 			"markerPath": keyMarkerPath,
 			"recursive":  recursive,
 			"maxUploads": maxUploads,
-		}).Errorf("listMetaVolumeFiles failed with %s", e)
-		return ListMultipartsInfo{}, probe.NewError(e)
+		}).Errorf("listMetaVolumeFiles failed with %s", err)
+		return ListMultipartsInfo{}, err
 	}
 
 	// Loop through all the received files fill in the multiparts result.
@@ -260,55 +250,50 @@ func (o objectAPI) ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarke
 	return result, nil
 }
 
-func (o objectAPI) NewMultipartUpload(bucket, object string) (string, *probe.Error) {
+func (fs fsObjects) NewMultipartUpload(bucket, object string) (string, error) {
 	// Verify if bucket name is valid.
 	if !IsValidBucketName(bucket) {
-		return "", probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return "", (BucketNameInvalid{Bucket: bucket})
 	}
 	// Verify if object name is valid.
 	if !IsValidObjectName(object) {
-		return "", probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
+		return "", ObjectNameInvalid{Bucket: bucket, Object: object}
 	}
 	// Verify whether the bucket exists.
-	isExist, err := o.isBucketExist(bucket)
-	if err != nil {
-		return "", probe.NewError(err)
-	}
-	if !isExist {
-		return "", probe.NewError(BucketNotFound{Bucket: bucket})
+	if isExist, err := isBucketExist(fs.storage, bucket); err != nil {
+		return "", err
+	} else if !isExist {
+		return "", BucketNotFound{Bucket: bucket}
 	}
 
-	if _, e := o.storage.StatVol(minioMetaVolume); e != nil {
-		if e == errVolumeNotFound {
-			e = o.storage.MakeVol(minioMetaVolume)
-			if e != nil {
-				if e == errDiskFull {
-					return "", probe.NewError(StorageFull{})
-				}
-				return "", probe.NewError(e)
+	if _, err := fs.storage.StatVol(minioMetaVolume); err != nil {
+		if err == errVolumeNotFound {
+			err = fs.storage.MakeVol(minioMetaVolume)
+			if err != nil {
+				return "", toObjectErr(err)
 			}
 		}
 	}
 	for {
-		uuid, e := uuid.New()
-		if e != nil {
-			return "", probe.NewError(e)
+		uuid, err := uuid.New()
+		if err != nil {
+			return "", err
 		}
 		uploadID := uuid.String()
 		uploadIDPath := path.Join(bucket, object, uploadID)
-		if _, e = o.storage.StatFile(minioMetaVolume, uploadIDPath); e != nil {
-			if e != errFileNotFound {
-				return "", probe.NewError(toObjectErr(e, minioMetaVolume, uploadIDPath))
+		if _, err = fs.storage.StatFile(minioMetaVolume, uploadIDPath); err != nil {
+			if err != errFileNotFound {
+				return "", (toObjectErr(err, minioMetaVolume, uploadIDPath))
 			}
 			// uploadIDPath doesn't exist, so create empty file to reserve the name
 			var w io.WriteCloser
-			if w, e = o.storage.CreateFile(minioMetaVolume, uploadIDPath); e == nil {
+			if w, err = fs.storage.CreateFile(minioMetaVolume, uploadIDPath); err == nil {
 				// Close the writer.
-				if e = w.Close(); e != nil {
-					return "", probe.NewError(e)
+				if err = w.Close(); err != nil {
+					return "", err
 				}
 			} else {
-				return "", probe.NewError(toObjectErr(e, minioMetaVolume, uploadIDPath))
+				return "", toObjectErr(err, minioMetaVolume, uploadIDPath)
 			}
 			return uploadID, nil
 		}
@@ -318,48 +303,46 @@ func (o objectAPI) NewMultipartUpload(bucket, object string) (string, *probe.Err
 }
 
 // isUploadIDExists - verify if a given uploadID exists and is valid.
-func (o objectAPI) isUploadIDExists(bucket, object, uploadID string) (bool, error) {
+func isUploadIDExists(storage StorageAPI, bucket, object, uploadID string) (bool, error) {
 	uploadIDPath := path.Join(bucket, object, uploadID)
-	st, e := o.storage.StatFile(minioMetaVolume, uploadIDPath)
-	if e != nil {
+	st, err := storage.StatFile(minioMetaVolume, uploadIDPath)
+	if err != nil {
 		// Upload id does not exist.
-		if e == errFileNotFound {
+		if err == errFileNotFound {
 			return false, nil
 		}
-		return false, e
+		return false, err
 	}
 	// Upload id exists and is a regular file.
 	return st.Mode.IsRegular(), nil
 }
 
 // PutObjectPart - writes the multipart upload chunks.
-func (o objectAPI) PutObjectPart(bucket, object, uploadID string, partID int, size int64, data io.Reader, md5Hex string) (string, *probe.Error) {
+func (fs fsObjects) PutObjectPart(bucket, object, uploadID string, partID int, size int64, data io.Reader, md5Hex string) (string, error) {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return "", probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return "", BucketNameInvalid{Bucket: bucket}
 	}
 	if !IsValidObjectName(object) {
-		return "", probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
+		return "", ObjectNameInvalid{Bucket: bucket, Object: object}
 	}
 	// Verify whether the bucket exists.
-	isExist, err := o.isBucketExist(bucket)
-	if err != nil {
-		return "", probe.NewError(err)
-	}
-	if !isExist {
-		return "", probe.NewError(BucketNotFound{Bucket: bucket})
+	if isExist, err := isBucketExist(fs.storage, bucket); err != nil {
+		return "", err
+	} else if !isExist {
+		return "", BucketNotFound{Bucket: bucket}
 	}
 
-	if status, e := o.isUploadIDExists(bucket, object, uploadID); e != nil {
-		return "", probe.NewError(e)
+	if status, err := isUploadIDExists(fs.storage, bucket, object, uploadID); err != nil {
+		return "", err
 	} else if !status {
-		return "", probe.NewError(InvalidUploadID{UploadID: uploadID})
+		return "", InvalidUploadID{UploadID: uploadID}
 	}
 
 	partSuffix := fmt.Sprintf("%s.%d.%s", uploadID, partID, md5Hex)
-	fileWriter, e := o.storage.CreateFile(minioMetaVolume, path.Join(bucket, object, partSuffix))
-	if e != nil {
-		return "", probe.NewError(toObjectErr(e, bucket, object))
+	fileWriter, err := fs.storage.CreateFile(minioMetaVolume, path.Join(bucket, object, partSuffix))
+	if err != nil {
+		return "", toObjectErr(err, bucket, object)
 	}
 
 	// Initialize md5 writer.
@@ -370,21 +353,21 @@ func (o objectAPI) PutObjectPart(bucket, object, uploadID string, partID int, si
 
 	// Instantiate checksum hashers and create a multiwriter.
 	if size > 0 {
-		if _, e = io.CopyN(multiWriter, data, size); e != nil {
+		if _, err = io.CopyN(multiWriter, data, size); err != nil {
 			safeCloseAndRemove(fileWriter)
-			return "", probe.NewError(toObjectErr(e))
+			return "", (toObjectErr(err))
 		}
 		// Reader shouldn't have more data what mentioned in size argument.
 		// reading one more byte from the reader to validate it.
 		// expected to fail, success validates existence of more data in the reader.
-		if _, e = io.CopyN(ioutil.Discard, data, 1); e == nil {
+		if _, err = io.CopyN(ioutil.Discard, data, 1); err == nil {
 			safeCloseAndRemove(fileWriter)
-			return "", probe.NewError(UnExpectedDataSize{Size: int(size)})
+			return "", (UnExpectedDataSize{Size: int(size)})
 		}
 	} else {
-		if _, e = io.Copy(multiWriter, data); e != nil {
+		if _, err = io.Copy(multiWriter, data); err != nil {
 			safeCloseAndRemove(fileWriter)
-			return "", probe.NewError(toObjectErr(e))
+			return "", (toObjectErr(err))
 		}
 	}
 
@@ -392,28 +375,28 @@ func (o objectAPI) PutObjectPart(bucket, object, uploadID string, partID int, si
 	if md5Hex != "" {
 		if newMD5Hex != md5Hex {
 			safeCloseAndRemove(fileWriter)
-			return "", probe.NewError(BadDigest{md5Hex, newMD5Hex})
+			return "", (BadDigest{md5Hex, newMD5Hex})
 		}
 	}
-	e = fileWriter.Close()
-	if e != nil {
-		return "", probe.NewError(e)
+	err = fileWriter.Close()
+	if err != nil {
+		return "", err
 	}
 	return newMD5Hex, nil
 }
 
-func (o objectAPI) ListObjectParts(bucket, object, uploadID string, partNumberMarker, maxParts int) (ListPartsInfo, *probe.Error) {
+func (fs fsObjects) ListObjectParts(bucket, object, uploadID string, partNumberMarker, maxParts int) (ListPartsInfo, error) {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return ListPartsInfo{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return ListPartsInfo{}, (BucketNameInvalid{Bucket: bucket})
 	}
 	if !IsValidObjectName(object) {
-		return ListPartsInfo{}, probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
+		return ListPartsInfo{}, (ObjectNameInvalid{Bucket: bucket, Object: object})
 	}
-	if status, e := o.isUploadIDExists(bucket, object, uploadID); e != nil {
-		return ListPartsInfo{}, probe.NewError(e)
+	if status, err := isUploadIDExists(fs.storage, bucket, object, uploadID); err != nil {
+		return ListPartsInfo{}, err
 	} else if !status {
-		return ListPartsInfo{}, probe.NewError(InvalidUploadID{UploadID: uploadID})
+		return ListPartsInfo{}, (InvalidUploadID{UploadID: uploadID})
 	}
 	result := ListPartsInfo{}
 	var markerPath string
@@ -423,26 +406,26 @@ func (o objectAPI) ListObjectParts(bucket, object, uploadID string, partNumberMa
 	// partNumberMarker is already set.
 	if partNumberMarker > 0 {
 		partNumberMarkerPath := uploadIDPath + "." + strconv.Itoa(partNumberMarker) + "."
-		fileInfos, _, e := o.storage.ListFiles(minioMetaVolume, partNumberMarkerPath, "", false, 1)
-		if e != nil {
-			return result, probe.NewError(toObjectErr(e, minioMetaVolume, partNumberMarkerPath))
+		fileInfos, _, err := fs.storage.ListFiles(minioMetaVolume, partNumberMarkerPath, "", false, 1)
+		if err != nil {
+			return result, toObjectErr(err, minioMetaVolume, partNumberMarkerPath)
 		}
 		if len(fileInfos) == 0 {
-			return result, probe.NewError(InvalidPart{})
+			return result, (InvalidPart{})
 		}
 		markerPath = fileInfos[0].Name
 	}
 	uploadIDPrefix := uploadIDPath + "."
-	fileInfos, eof, e := o.storage.ListFiles(minioMetaVolume, uploadIDPrefix, markerPath, false, maxParts)
-	if e != nil {
-		return result, probe.NewError(InvalidPart{})
+	fileInfos, eof, err := fs.storage.ListFiles(minioMetaVolume, uploadIDPrefix, markerPath, false, maxParts)
+	if err != nil {
+		return result, InvalidPart{}
 	}
 	for _, fileInfo := range fileInfos {
 		fileName := path.Base(fileInfo.Name)
 		splitResult := strings.Split(fileName, ".")
-		partNum, e := strconv.Atoi(splitResult[1])
-		if e != nil {
-			return result, probe.NewError(e)
+		partNum, err := strconv.Atoi(splitResult[1])
+		if err != nil {
+			return result, err
 		}
 		md5sum := splitResult[2]
 		result.Parts = append(result.Parts, partInfo{
@@ -463,86 +446,90 @@ func (o objectAPI) ListObjectParts(bucket, object, uploadID string, partNumberMa
 	return result, nil
 }
 
-// Create an s3 compatible MD5sum for complete multipart transaction.
-func makeS3MD5(md5Strs ...string) (string, *probe.Error) {
-	var finalMD5Bytes []byte
-	for _, md5Str := range md5Strs {
-		md5Bytes, e := hex.DecodeString(md5Str)
-		if e != nil {
-			return "", probe.NewError(e)
-		}
-		finalMD5Bytes = append(finalMD5Bytes, md5Bytes...)
-	}
-	md5Hasher := md5.New()
-	md5Hasher.Write(finalMD5Bytes)
-	s3MD5 := fmt.Sprintf("%s-%d", hex.EncodeToString(md5Hasher.Sum(nil)), len(md5Strs))
-	return s3MD5, nil
-}
-
-func (o objectAPI) CompleteMultipartUpload(bucket string, object string, uploadID string, parts []completePart) (string, *probe.Error) {
+func (fs fsObjects) CompleteMultipartUpload(bucket string, object string, uploadID string, parts []completePart) (string, error) {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return "", probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return "", (BucketNameInvalid{Bucket: bucket})
 	}
 	if !IsValidObjectName(object) {
-		return "", probe.NewError(ObjectNameInvalid{
+		return "", (ObjectNameInvalid{
 			Bucket: bucket,
 			Object: object,
 		})
 	}
-	if status, e := o.isUploadIDExists(bucket, object, uploadID); e != nil {
-		return "", probe.NewError(e)
+	if status, err := isUploadIDExists(fs.storage, bucket, object, uploadID); err != nil {
+		return "", err
 	} else if !status {
-		return "", probe.NewError(InvalidUploadID{UploadID: uploadID})
+		return "", (InvalidUploadID{UploadID: uploadID})
+	}
+
+	fileWriter, err := fs.storage.CreateFile(bucket, object)
+	if err != nil {
+		return "", toObjectErr(err, bucket, object)
 	}
 
 	var md5Sums []string
 	for _, part := range parts {
 		// Construct part suffix.
 		partSuffix := fmt.Sprintf("%s.%d.%s", uploadID, part.PartNumber, part.ETag)
-		e := o.storage.RenameFile(minioMetaVolume, path.Join(bucket, object, partSuffix), bucket, path.Join(object, fmt.Sprint(part.PartNumber)))
-		if e != nil {
-			return "", probe.NewError(e)
+		var fileReader io.ReadCloser
+		fileReader, err = fs.storage.ReadFile(minioMetaVolume, path.Join(bucket, object, partSuffix), 0)
+		if err != nil {
+			if err == errFileNotFound {
+				return "", (InvalidPart{})
+			}
+			return "", err
+		}
+		_, err = io.Copy(fileWriter, fileReader)
+		if err != nil {
+			return "", err
+		}
+		err = fileReader.Close()
+		if err != nil {
+			return "", err
 		}
 		md5Sums = append(md5Sums, part.ETag)
 	}
-	fileWriter, e := o.storage.CreateFile(bucket, path.Join(object, "multipart.json"))
-	if e != nil {
-		return "", probe.NewError(e)
+
+	err = fileWriter.Close()
+	if err != nil {
+		return "", err
 	}
-	fileWriter.Close()
+
 	// Save the s3 md5.
 	s3MD5, err := makeS3MD5(md5Sums...)
 	if err != nil {
-		return "", err.Trace(md5Sums...)
+		return "", err
 	}
 
 	// Cleanup all the parts.
-	// o.removeMultipartUpload(bucket, object, uploadID)
+	fs.removeMultipartUpload(bucket, object, uploadID)
 
 	// Return md5sum.
 	return s3MD5, nil
 }
 
-func (o objectAPI) removeMultipartUpload(bucket, object, uploadID string) *probe.Error {
+func (fs fsObjects) removeMultipartUpload(bucket, object, uploadID string) error {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return (BucketNameInvalid{Bucket: bucket})
 	}
 	if !IsValidObjectName(object) {
-		return probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
+		return (ObjectNameInvalid{Bucket: bucket, Object: object})
 	}
 
 	marker := ""
 	for {
 		uploadIDPath := path.Join(bucket, object, uploadID)
-		fileInfos, eof, e := o.storage.ListFiles(minioMetaVolume, uploadIDPath, marker, false, 1000)
-		if e != nil {
-
-			return probe.NewError(InvalidUploadID{UploadID: uploadID})
+		fileInfos, eof, err := fs.storage.ListFiles(minioMetaVolume, uploadIDPath, marker, false, 1000)
+		if err != nil {
+			if err == errFileNotFound {
+				return (InvalidUploadID{UploadID: uploadID})
+			}
+			return toObjectErr(err)
 		}
 		for _, fileInfo := range fileInfos {
-			o.storage.DeleteFile(minioMetaVolume, fileInfo.Name)
+			fs.storage.DeleteFile(minioMetaVolume, fileInfo.Name)
 			marker = fileInfo.Name
 		}
 		if eof {
@@ -552,22 +539,18 @@ func (o objectAPI) removeMultipartUpload(bucket, object, uploadID string) *probe
 	return nil
 }
 
-func (o objectAPI) AbortMultipartUpload(bucket, object, uploadID string) *probe.Error {
+func (fs fsObjects) AbortMultipartUpload(bucket, object, uploadID string) error {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return (BucketNameInvalid{Bucket: bucket})
 	}
 	if !IsValidObjectName(object) {
-		return probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
+		return (ObjectNameInvalid{Bucket: bucket, Object: object})
 	}
-	if status, e := o.isUploadIDExists(bucket, object, uploadID); e != nil {
-		return probe.NewError(e)
+	if status, err := isUploadIDExists(fs.storage, bucket, object, uploadID); err != nil {
+		return err
 	} else if !status {
-		return probe.NewError(InvalidUploadID{UploadID: uploadID})
+		return (InvalidUploadID{UploadID: uploadID})
 	}
-	err := o.removeMultipartUpload(bucket, object, uploadID)
-	if err != nil {
-		return err.Trace(bucket, object, uploadID)
-	}
-	return nil
+	return fs.removeMultipartUpload(bucket, object, uploadID)
 }
diff --git a/fs-objects.go b/fs-objects.go
new file mode 100644
index 000000000..35171ebf7
--- /dev/null
+++ b/fs-objects.go
@@ -0,0 +1,333 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+	"io"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"github.com/minio/minio/pkg/mimedb"
+)
+
+// fsObjects - Implements fs object layer.
+type fsObjects struct {
+	storage StorageAPI
+}
+
+// newFSObjects - initialize new fs object layer.
+func newFSObjects(exportPath string) (ObjectLayer, error) {
+	var storage StorageAPI
+	var err error
+	if !strings.ContainsRune(exportPath, ':') || filepath.VolumeName(exportPath) != "" {
+		// Initialize filesystem storage API.
+		storage, err = newPosix(exportPath)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		// Initialize rpc client storage API.
+		storage, err = newRPCClient(exportPath)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return fsObjects{storage}, nil
+}
+
+// checks whether bucket exists.
+func isBucketExist(storage StorageAPI, bucketName string) (bool, error) {
+	// Check whether bucket exists.
+	if _, e := storage.StatVol(bucketName); e != nil {
+		if e == errVolumeNotFound {
+			return false, nil
+		}
+		return false, e
+	}
+	return true, nil
+}
+
+/// Bucket operations
+
+// MakeBucket - make a bucket.
+func (fs fsObjects) MakeBucket(bucket string) error {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return BucketNameInvalid{Bucket: bucket}
+	}
+	if err := fs.storage.MakeVol(bucket); err != nil {
+		return toObjectErr(err, bucket)
+	}
+	// This happens for the first time, but keep this here since this
+	// is the only place where it can be made expensive optimizing all
+	// other calls.
+	// Create minio meta volume, if it doesn't exist yet.
+	if err := fs.storage.MakeVol(minioMetaVolume); err != nil {
+		if err != errVolumeExists {
+			return toObjectErr(err, minioMetaVolume)
+		}
+	}
+	return nil
+}
+
+// GetBucketInfo - get bucket info.
+func (fs fsObjects) GetBucketInfo(bucket string) (BucketInfo, error) {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return BucketInfo{}, BucketNameInvalid{Bucket: bucket}
+	}
+	vi, err := fs.storage.StatVol(bucket)
+	if err != nil {
+		return BucketInfo{}, toObjectErr(err, bucket)
+	}
+	return BucketInfo{
+		Name:    bucket,
+		Created: vi.Created,
+		Total:   vi.Total,
+		Free:    vi.Free,
+	}, nil
+}
+
+// ListBuckets - list buckets.
+func (fs fsObjects) ListBuckets() ([]BucketInfo, error) {
+	var bucketInfos []BucketInfo
+	vols, err := fs.storage.ListVols()
+	if err != nil {
+		return nil, toObjectErr(err)
+	}
+	for _, vol := range vols {
+		// StorageAPI can send volume names which are incompatible
+		// with buckets, handle it and skip them.
+		if !IsValidBucketName(vol.Name) {
+			continue
+		}
+		bucketInfos = append(bucketInfos, BucketInfo{
+			Name:    vol.Name,
+			Created: vol.Created,
+			Total:   vol.Total,
+			Free:    vol.Free,
+		})
+	}
+	sort.Sort(byBucketName(bucketInfos))
+	return bucketInfos, nil
+}
+
+// DeleteBucket - delete a bucket.
+func (fs fsObjects) DeleteBucket(bucket string) error {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return BucketNameInvalid{Bucket: bucket}
+	}
+	if err := fs.storage.DeleteVol(bucket); err != nil {
+		return toObjectErr(err)
+	}
+	return nil
+}
+
+/// Object Operations
+
+// GetObject - get an object.
+func (fs fsObjects) GetObject(bucket, object string, startOffset int64) (io.ReadCloser, error) {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return nil, (BucketNameInvalid{Bucket: bucket})
+	}
+	// Verify if object is valid.
+	if !IsValidObjectName(object) {
+		return nil, (ObjectNameInvalid{Bucket: bucket, Object: object})
+	}
+	fileReader, err := fs.storage.ReadFile(bucket, object, startOffset)
+	if err != nil {
+		return nil, toObjectErr(err, bucket, object)
+	}
+	return fileReader, nil
+}
+
+// GetObjectInfo - get object info.
+func (fs fsObjects) GetObjectInfo(bucket, object string) (ObjectInfo, error) {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return ObjectInfo{}, (BucketNameInvalid{Bucket: bucket})
+	}
+	// Verify if object is valid.
+	if !IsValidObjectName(object) {
+		return ObjectInfo{}, (ObjectNameInvalid{Bucket: bucket, Object: object})
+	}
+	fi, err := fs.storage.StatFile(bucket, object)
+	if err != nil {
+		return ObjectInfo{}, toObjectErr(err, bucket, object)
+	}
+	contentType := "application/octet-stream"
+	if objectExt := filepath.Ext(object); objectExt != "" {
+		content, ok := mimedb.DB[strings.ToLower(strings.TrimPrefix(objectExt, "."))]
+		if ok {
+			contentType = content.ContentType
+		}
+	}
+	return ObjectInfo{
+		Bucket:      bucket,
+		Name:        object,
+		ModTime:     fi.ModTime,
+		Size:        fi.Size,
+		IsDir:       fi.Mode.IsDir(),
+		ContentType: contentType,
+		MD5Sum:      "", // Read from metadata.
+	}, nil
+}
+
+func (fs fsObjects) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string) (string, error) {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return "", (BucketNameInvalid{Bucket: bucket})
+	}
+	if !IsValidObjectName(object) {
+		return "", (ObjectNameInvalid{
+			Bucket: bucket,
+			Object: object,
+		})
+	}
+	// Check whether the bucket exists.
+	if isExist, err := isBucketExist(fs.storage, bucket); err != nil {
+		return "", err
+	} else if !isExist {
+		return "", BucketNotFound{Bucket: bucket}
+	}
+
+	fileWriter, err := fs.storage.CreateFile(bucket, object)
+	if err != nil {
+		return "", toObjectErr(err, bucket, object)
+	}
+
+	// Initialize md5 writer.
+	md5Writer := md5.New()
+
+	// Instantiate a new multi writer.
+	multiWriter := io.MultiWriter(md5Writer, fileWriter)
+
+	// Instantiate checksum hashers and create a multiwriter.
+	if size > 0 {
+		if _, err = io.CopyN(multiWriter, data, size); err != nil {
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", clErr
+			}
+			return "", toObjectErr(err)
+		}
+	} else {
+		if _, err = io.Copy(multiWriter, data); err != nil {
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", clErr
+			}
+			return "", err
+		}
+	}
+
+	newMD5Hex := hex.EncodeToString(md5Writer.Sum(nil))
+	// md5Hex representation.
+	var md5Hex string
+	if len(metadata) != 0 {
+		md5Hex = metadata["md5Sum"]
+	}
+	if md5Hex != "" {
+		if newMD5Hex != md5Hex {
+			if err = safeCloseAndRemove(fileWriter); err != nil {
+				return "", err
+			}
+			return "", BadDigest{md5Hex, newMD5Hex}
+		}
+	}
+	err = fileWriter.Close()
+	if err != nil {
+		return "", err
+	}
+
+	// Return md5sum, successfully wrote object.
+	return newMD5Hex, nil
+}
+
+func (fs fsObjects) DeleteObject(bucket, object string) error {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return BucketNameInvalid{Bucket: bucket}
+	}
+	if !IsValidObjectName(object) {
+		return ObjectNameInvalid{Bucket: bucket, Object: object}
+	}
+	if err := fs.storage.DeleteFile(bucket, object); err != nil {
+		return toObjectErr(err, bucket, object)
+	}
+	return nil
+}
+
+func (fs fsObjects) ListObjects(bucket, prefix, marker, delimiter string, maxKeys int) (ListObjectsInfo, error) {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return ListObjectsInfo{}, BucketNameInvalid{Bucket: bucket}
+	}
+	if !IsValidObjectPrefix(prefix) {
+		return ListObjectsInfo{}, ObjectNameInvalid{Bucket: bucket, Object: prefix}
+	}
+	// Verify if delimiter is anything other than '/', which we do not support.
+	if delimiter != "" && delimiter != slashSeparator {
+		return ListObjectsInfo{}, UnsupportedDelimiter{
+			Delimiter: delimiter,
+		}
+	}
+	// Verify if marker has prefix.
+	if marker != "" {
+		if !strings.HasPrefix(marker, prefix) {
+			return ListObjectsInfo{}, InvalidMarkerPrefixCombination{
+				Marker: marker,
+				Prefix: prefix,
+			}
+		}
+	}
+
+	// Default is recursive, if delimiter is set then list non recursive.
+	recursive := true
+	if delimiter == slashSeparator {
+		recursive = false
+	}
+	fileInfos, eof, err := fs.storage.ListFiles(bucket, prefix, marker, recursive, maxKeys)
+	if err != nil {
+		return ListObjectsInfo{}, toObjectErr(err, bucket)
+	}
+	if maxKeys == 0 {
+		return ListObjectsInfo{}, nil
+	}
+
+	result := ListObjectsInfo{IsTruncated: !eof}
+	for _, fileInfo := range fileInfos {
+		// With delimiter set we fill in NextMarker and Prefixes.
+		if delimiter == slashSeparator {
+			result.NextMarker = fileInfo.Name
+			if fileInfo.Mode.IsDir() {
+				result.Prefixes = append(result.Prefixes, fileInfo.Name)
+				continue
+			}
+		}
+		result.Objects = append(result.Objects, ObjectInfo{
+			Name:    fileInfo.Name,
+			ModTime: fileInfo.ModTime,
+			Size:    fileInfo.Size,
+			IsDir:   false,
+		})
+	}
+	return result, nil
+}
diff --git a/httprange.go b/httprange.go
index cc32a946f..b00a37771 100644
--- a/httprange.go
+++ b/httprange.go
@@ -21,8 +21,6 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
-
-	"github.com/minio/minio/pkg/probe"
 )
 
 const (
@@ -50,7 +48,7 @@ func (r *httpRange) String() string {
 }
 
 // Grab new range from request header
-func getRequestedRange(hrange string, size int64) (*httpRange, *probe.Error) {
+func getRequestedRange(hrange string, size int64) (*httpRange, error) {
 	r := &httpRange{
 		start:  0,
 		length: 0,
@@ -60,16 +58,16 @@ func getRequestedRange(hrange string, size int64) (*httpRange, *probe.Error) {
 	if hrange != "" {
 		err := r.parseRange(hrange)
 		if err != nil {
-			return nil, err.Trace()
+			return nil, err
 		}
 	}
 	return r, nil
 }
 
-func (r *httpRange) parse(ra string) *probe.Error {
+func (r *httpRange) parse(ra string) error {
 	i := strings.Index(ra, "-")
 	if i < 0 {
-		return probe.NewError(InvalidRange{})
+		return InvalidRange{}
 	}
 	start, end := strings.TrimSpace(ra[:i]), strings.TrimSpace(ra[i+1:])
 	if start == "" {
@@ -77,7 +75,7 @@ func (r *httpRange) parse(ra string) *probe.Error {
 		// range start relative to the end of the file.
 		i, err := strconv.ParseInt(end, 10, 64)
 		if err != nil {
-			return probe.NewError(InvalidRange{})
+			return InvalidRange{}
 		}
 		if i > r.size {
 			i = r.size
@@ -87,7 +85,7 @@ func (r *httpRange) parse(ra string) *probe.Error {
 	} else {
 		i, err := strconv.ParseInt(start, 10, 64)
 		if err != nil || i > r.size || i < 0 {
-			return probe.NewError(InvalidRange{})
+			return InvalidRange{}
 		}
 		r.start = i
 		if end == "" {
@@ -96,7 +94,7 @@ func (r *httpRange) parse(ra string) *probe.Error {
 		} else {
 			i, err := strconv.ParseInt(end, 10, 64)
 			if err != nil || r.start > i {
-				return probe.NewError(InvalidRange{})
+				return InvalidRange{}
 			}
 			if i >= r.size {
 				i = r.size - 1
@@ -108,26 +106,26 @@ func (r *httpRange) parse(ra string) *probe.Error {
 }
 
 // parseRange parses a Range header string as per RFC 2616.
-func (r *httpRange) parseRange(s string) *probe.Error {
+func (r *httpRange) parseRange(s string) error {
 	if s == "" {
-		return probe.NewError(errors.New("header not present"))
+		return errors.New("header not present")
 	}
 	if !strings.HasPrefix(s, b) {
-		return probe.NewError(InvalidRange{})
+		return InvalidRange{}
 	}
 
 	ras := strings.Split(s[len(b):], ",")
 	if len(ras) == 0 {
-		return probe.NewError(errors.New("invalid request"))
+		return errors.New("invalid request")
 	}
 	// Just pick the first one and ignore the rest, we only support one range per object
 	if len(ras) > 1 {
-		return probe.NewError(errors.New("multiple ranges specified"))
+		return errors.New("multiple ranges specified")
 	}
 
 	ra := strings.TrimSpace(ras[0])
 	if ra == "" {
-		return probe.NewError(InvalidRange{})
+		return InvalidRange{}
 	}
 	return r.parse(ra)
 }
diff --git a/logger-console-hook.go b/logger-console-hook.go
index f1455a54d..506bb23ea 100644
--- a/logger-console-hook.go
+++ b/logger-console-hook.go
@@ -20,7 +20,6 @@ import (
 	"io/ioutil"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/minio/minio/pkg/probe"
 )
 
 // consoleLogger - default logger if not other logging is enabled.
@@ -39,8 +38,8 @@ func enableConsoleLogger() {
 	}
 	// log.Out and log.Formatter use the default versions.
 	// Only set specific log level.
-	lvl, e := logrus.ParseLevel(clogger.Level)
-	fatalIf(probe.NewError(e), "Unknown log level detected, please fix your console logger configuration.", nil)
+	lvl, err := logrus.ParseLevel(clogger.Level)
+	fatalIf(err, "Unknown log level detected, please fix your console logger configuration.", nil)
 
 	log.Level = lvl
 }
diff --git a/logger-file-hook.go b/logger-file-hook.go
index aaedf74a6..ed84f2841 100644
--- a/logger-file-hook.go
+++ b/logger-file-hook.go
@@ -21,7 +21,6 @@ import (
 	"os"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/minio/minio/pkg/probe"
 )
 
 type fileLogger struct {
@@ -40,14 +39,14 @@ func enableFileLogger() {
 		return
 	}
 
-	file, e := os.OpenFile(flogger.Filename, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
-	fatalIf(probe.NewError(e), "Unable to open log file.", nil)
+	file, err := os.OpenFile(flogger.Filename, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
+	fatalIf(err, "Unable to open log file.", nil)
 
 	// Add a local file hook.
 	log.Hooks.Add(&localFile{file})
 
-	lvl, e := logrus.ParseLevel(flogger.Level)
-	fatalIf(probe.NewError(e), "Unknown log level detected, please fix your console logger configuration.", nil)
+	lvl, err := logrus.ParseLevel(flogger.Level)
+	fatalIf(err, "Unknown log level detected, please fix your console logger configuration.", nil)
 
 	// Set default JSON formatter.
 	log.Formatter = new(logrus.JSONFormatter)
diff --git a/logger-syslog-hook_nix.go b/logger-syslog-hook_nix.go
index 8423c73c9..aeac4eefc 100644
--- a/logger-syslog-hook_nix.go
+++ b/logger-syslog-hook_nix.go
@@ -23,7 +23,6 @@ import (
 	"log/syslog"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/minio/minio/pkg/probe"
 )
 
 type syslogLogger struct {
@@ -41,8 +40,8 @@ type syslogHook struct {
 
 // enableSyslogLogger - enable logger at raddr.
 func enableSyslogLogger(raddr string) {
-	syslogHook, e := newSyslog("udp", raddr, syslog.LOG_ERR, "MINIO")
-	fatalIf(probe.NewError(e), "Unable to instantiate syslog.", nil)
+	syslogHook, err := newSyslog("udp", raddr, syslog.LOG_ERR, "MINIO")
+	fatalIf(err, "Unable to instantiate syslog.", nil)
 
 	log.Hooks.Add(syslogHook)               // Add syslog hook.
 	log.Formatter = &logrus.JSONFormatter{} // JSON formatted log.
@@ -51,15 +50,15 @@ func enableSyslogLogger(raddr string) {
 
 // newSyslog - Creates a hook to be added to an instance of logger.
 func newSyslog(network, raddr string, priority syslog.Priority, tag string) (*syslogHook, error) {
-	w, e := syslog.Dial(network, raddr, priority, tag)
-	return &syslogHook{w, network, raddr}, e
+	w, err := syslog.Dial(network, raddr, priority, tag)
+	return &syslogHook{w, network, raddr}, err
 }
 
 // Fire - fire the log event
 func (hook *syslogHook) Fire(entry *logrus.Entry) error {
-	line, e := entry.String()
-	if e != nil {
-		return fmt.Errorf("Unable to read entry, %v", e)
+	line, err := entry.String()
+	if err != nil {
+		return fmt.Errorf("Unable to read entry, %v", err)
 	}
 	switch entry.Level {
 	case logrus.PanicLevel:
diff --git a/logger-syslog-hook_windows.go b/logger-syslog-hook_windows.go
index 9013c1b80..3628c4248 100644
--- a/logger-syslog-hook_windows.go
+++ b/logger-syslog-hook_windows.go
@@ -18,8 +18,6 @@
 
 package main
 
-import "github.com/minio/minio/pkg/probe"
-
 type syslogLogger struct {
 	Enable bool   `json:"enable"`
 	Addr   string `json:"address"`
@@ -28,5 +26,5 @@ type syslogLogger struct {
 
 // enableSyslogLogger - unsupported on windows.
 func enableSyslogLogger(raddr string) {
-	fatalIf(probe.NewError(errSyslogNotSupported), "Unable to enable syslog.", nil)
+	fatalIf(errSyslogNotSupported, "Unable to enable syslog.", nil)
 }
diff --git a/logger.go b/logger.go
index 1cd2ab49d..4683e6b6c 100644
--- a/logger.go
+++ b/logger.go
@@ -17,11 +17,9 @@
 package main
 
 import (
-	"encoding/json"
 	"reflect"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/minio/minio/pkg/probe"
 )
 
 type fields map[string]interface{}
@@ -43,7 +41,7 @@ type logger struct {
 }
 
 // errorIf synonymous with fatalIf but doesn't exit on error != nil
-func errorIf(err *probe.Error, msg string, fields logrus.Fields) {
+func errorIf(err error, msg string, fields logrus.Fields) {
 	if err == nil {
 		return
 	}
@@ -51,21 +49,17 @@ func errorIf(err *probe.Error, msg string, fields logrus.Fields) {
 		fields = make(logrus.Fields)
 	}
 	fields["Error"] = struct {
-		Cause     string             `json:"cause,omitempty"`
-		Type      string             `json:"type,omitempty"`
-		CallTrace []probe.TracePoint `json:"trace,omitempty"`
-		SysInfo   map[string]string  `json:"sysinfo,omitempty"`
+		Cause string `json:"cause,omitempty"`
+		Type  string `json:"type,omitempty"`
 	}{
-		err.Cause.Error(),
-		reflect.TypeOf(err.Cause).String(),
-		err.CallTrace,
-		err.SysInfo,
+		err.Error(),
+		reflect.TypeOf(err).String(),
 	}
 	log.WithFields(fields).Error(msg)
 }
 
 // fatalIf wrapper function which takes error and prints jsonic error messages.
-func fatalIf(err *probe.Error, msg string, fields logrus.Fields) {
+func fatalIf(err error, msg string, fields logrus.Fields) {
 	if err == nil {
 		return
 	}
@@ -73,9 +67,12 @@ func fatalIf(err *probe.Error, msg string, fields logrus.Fields) {
 		fields = make(logrus.Fields)
 	}
 
-	fields["error"] = err.ToGoError()
-	if jsonErr, e := json.Marshal(err); e == nil {
-		fields["probe"] = string(jsonErr)
+	fields["Error"] = struct {
+		Cause string `json:"cause,omitempty"`
+		Type  string `json:"type,omitempty"`
+	}{
+		err.Error(),
+		reflect.TypeOf(err).String(),
 	}
 	log.WithFields(fields).Fatal(msg)
 }
diff --git a/logger_test.go b/logger_test.go
index 09c654218..6c96fef19 100644
--- a/logger_test.go
+++ b/logger_test.go
@@ -22,7 +22,6 @@ import (
 	"errors"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/minio/minio/pkg/probe"
 
 	. "gopkg.in/check.v1"
 )
@@ -37,7 +36,7 @@ func (s *LoggerSuite) TestLogger(c *C) {
 	log.Out = &buffer
 	log.Formatter = new(logrus.JSONFormatter)
 
-	errorIf(probe.NewError(errors.New("Fake error")), "Failed with error.", nil)
+	errorIf(errors.New("Fake error"), "Failed with error.", nil)
 	err := json.Unmarshal(buffer.Bytes(), &fields)
 	c.Assert(err, IsNil)
 	c.Assert(fields["level"], Equals, "error")
diff --git a/main.go b/main.go
index e732e6c95..ebaa2f709 100644
--- a/main.go
+++ b/main.go
@@ -197,7 +197,7 @@ func main() {
 
 		// Initialize config.
 		err := initConfig()
-		fatalIf(err.Trace(), "Unable to initialize minio config.", nil)
+		fatalIf(err, "Unable to initialize minio config.", nil)
 
 		// Enable all loggers by now.
 		enableLoggers()
diff --git a/notifier.go b/notifier.go
index 91cf54e14..5943ec524 100644
--- a/notifier.go
+++ b/notifier.go
@@ -22,12 +22,11 @@ import (
 	"strings"
 
 	"github.com/fatih/color"
-	"github.com/minio/minio/pkg/probe"
 	"github.com/olekukonko/ts"
 )
 
 // colorizeUpdateMessage - inspired from Yeoman project npm package https://github.com/yeoman/update-notifier
-func colorizeUpdateMessage(updateString string) (string, *probe.Error) {
+func colorizeUpdateMessage(updateString string) (string, error) {
 	// Initialize coloring.
 	cyan := color.New(color.FgCyan, color.Bold).SprintFunc()
 	yellow := color.New(color.FgYellow, color.Bold).SprintfFunc()
@@ -47,7 +46,7 @@ func colorizeUpdateMessage(updateString string) (string, *probe.Error) {
 
 	terminal, err := ts.GetSize()
 	if err != nil {
-		return "", probe.NewError(err)
+		return "", err
 	}
 
 	var message string
diff --git a/object-api-getobjectinfo_test.go b/object-api-getobjectinfo_test.go
index 82a473e89..cccf8ebf1 100644
--- a/object-api-getobjectinfo_test.go
+++ b/object-api-getobjectinfo_test.go
@@ -25,27 +25,22 @@ import (
 	"os"
 	"strconv"
 	"testing"
-
-	"github.com/minio/minio/pkg/probe"
 )
 
 // Testing GetObjectInfo().
 func TestGetObjectInfo(t *testing.T) {
-	directory, e := ioutil.TempDir("", "minio-get-objinfo-test")
-	if e != nil {
-		t.Fatal(e)
+	directory, err := ioutil.TempDir("", "minio-get-objinfo-test")
+	if err != nil {
+		t.Fatal(err)
 	}
 	defer os.RemoveAll(directory)
 
 	// Create the obj.
-	fs, e := newFS(directory)
-	if e != nil {
-		t.Fatal(e)
+	obj, err := newFSObjects(directory)
+	if err != nil {
+		t.Fatal(err)
 	}
 
-	obj := newObjectLayer(fs)
-	var err *probe.Error
-
 	// This bucket is used for testing getObjectInfo operations.
 	err = obj.MakeBucket("test-getobjectinfo")
 	if err != nil {
@@ -93,15 +88,15 @@ func TestGetObjectInfo(t *testing.T) {
 	for i, testCase := range testCases {
 		result, err := obj.GetObjectInfo(testCase.bucketName, testCase.objectName)
 		if err != nil && testCase.shouldPass {
-			t.Errorf("Test %d: Expected to pass, but failed with: <ERROR> %s", i+1, err.Cause.Error())
+			t.Errorf("Test %d: Expected to pass, but failed with: <ERROR> %s", i+1, err.Error())
 		}
 		if err == nil && !testCase.shouldPass {
 			t.Errorf("Test %d: Expected to fail with <ERROR> \"%s\", but passed instead", i+1, testCase.err.Error())
 		}
 		// Failed as expected, but does it fail for the expected reason.
 		if err != nil && !testCase.shouldPass {
-			if testCase.err.Error() != err.Cause.Error() {
-				t.Errorf("Test %d: Expected to fail with error \"%s\", but instead failed with error \"%s\" instead", i+1, testCase.err.Error(), err.Cause.Error())
+			if testCase.err.Error() != err.Error() {
+				t.Errorf("Test %d: Expected to fail with error \"%s\", but instead failed with error \"%s\" instead", i+1, testCase.err.Error(), err.Error())
 			}
 		}
 
@@ -125,21 +120,18 @@ func TestGetObjectInfo(t *testing.T) {
 
 func BenchmarkGetObject(b *testing.B) {
 	// Make a temporary directory to use as the obj.
-	directory, e := ioutil.TempDir("", "minio-benchmark-getobject")
-	if e != nil {
-		b.Fatal(e)
+	directory, err := ioutil.TempDir("", "minio-benchmark-getobject")
+	if err != nil {
+		b.Fatal(err)
 	}
 	defer os.RemoveAll(directory)
 
 	// Create the obj.
-	fs, e := newFS(directory)
-	if e != nil {
-		b.Fatal(e)
+	obj, err := newFSObjects(directory)
+	if err != nil {
+		b.Fatal(err)
 	}
 
-	obj := newObjectLayer(fs)
-	var err *probe.Error
-
 	// Make a bucket and put in a few objects.
 	err = obj.MakeBucket("bucket")
 	if err != nil {
@@ -165,8 +157,8 @@ func BenchmarkGetObject(b *testing.B) {
 		if err != nil {
 			b.Error(err)
 		}
-		if _, e := io.Copy(buffer, r); e != nil {
-			b.Error(e)
+		if _, err := io.Copy(buffer, r); err != nil {
+			b.Error(err)
 		}
 		if buffer.Len() != len(text) {
 			b.Errorf("GetObject returned incorrect length %d (should be %d)\n", buffer.Len(), len(text))
diff --git a/object-api-listobjects_test.go b/object-api-listobjects_test.go
index bb8079a16..90310f467 100644
--- a/object-api-listobjects_test.go
+++ b/object-api-listobjects_test.go
@@ -24,26 +24,22 @@ import (
 	"strconv"
 	"strings"
 	"testing"
-
-	"github.com/minio/minio/pkg/probe"
 )
 
 func TestListObjects(t *testing.T) {
 	// Make a temporary directory to use as the obj.
-	directory, e := ioutil.TempDir("", "minio-list-object-test")
-	if e != nil {
-		t.Fatal(e)
+	directory, err := ioutil.TempDir("", "minio-list-object-test")
+	if err != nil {
+		t.Fatal(err)
 	}
 	defer os.RemoveAll(directory)
 
 	// Create the obj.
-	fs, e := newFS(directory)
-	if e != nil {
-		t.Fatal(e)
+	obj, err := newFSObjects(directory)
+	if err != nil {
+		t.Fatal(err)
 	}
 
-	obj := newObjectLayer(fs)
-	var err *probe.Error
 	// This bucket is used for testing ListObject operations.
 	err = obj.MakeBucket("test-bucket-list-object")
 	if err != nil {
@@ -56,25 +52,25 @@ func TestListObjects(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	tmpfile, e := ioutil.TempFile("", "simple-file.txt")
-	if e != nil {
-		t.Fatal(e)
+	tmpfile, err := ioutil.TempFile("", "simple-file.txt")
+	if err != nil {
+		t.Fatal(err)
 	}
 	defer os.Remove(tmpfile.Name()) // clean up
 
 	_, err = obj.PutObject("test-bucket-list-object", "Asia-maps", int64(len("asia-maps")), bytes.NewBufferString("asia-maps"), nil)
 	if err != nil {
-		t.Fatal(e)
+		t.Fatal(err)
 	}
 
 	_, err = obj.PutObject("test-bucket-list-object", "Asia/India/India-summer-photos-1", int64(len("contentstring")), bytes.NewBufferString("contentstring"), nil)
 	if err != nil {
-		t.Fatal(e)
+		t.Fatal(err)
 	}
 
 	_, err = obj.PutObject("test-bucket-list-object", "Asia/India/Karnataka/Bangalore/Koramangala/pics", int64(len("contentstring")), bytes.NewBufferString("contentstring"), nil)
 	if err != nil {
-		t.Fatal(e)
+		t.Fatal(err)
 	}
 
 	for i := 0; i < 2; i++ {
@@ -86,7 +82,7 @@ func TestListObjects(t *testing.T) {
 	}
 	_, err = obj.PutObject("test-bucket-list-object", "newzen/zen/recurse/again/again/again/pics", int64(len("recurse")), bytes.NewBufferString("recurse"), nil)
 	if err != nil {
-		t.Fatal(e)
+		t.Fatal(err)
 	}
 
 	for i := 0; i < 3; i++ {
@@ -536,15 +532,15 @@ func TestListObjects(t *testing.T) {
 	for i, testCase := range testCases {
 		result, err := obj.ListObjects(testCase.bucketName, testCase.prefix, testCase.marker, testCase.delimeter, testCase.maxKeys)
 		if err != nil && testCase.shouldPass {
-			t.Errorf("Test %d: Expected to pass, but failed with: <ERROR> %s", i+1, err.Cause.Error())
+			t.Errorf("Test %d: Expected to pass, but failed with: <ERROR> %s", i+1, err.Error())
 		}
 		if err == nil && !testCase.shouldPass {
 			t.Errorf("Test %d: Expected to fail with <ERROR> \"%s\", but passed instead", i+1, testCase.err.Error())
 		}
 		// Failed as expected, but does it fail for the expected reason.
 		if err != nil && !testCase.shouldPass {
-			if !strings.Contains(err.Cause.Error(), testCase.err.Error()) {
-				t.Errorf("Test %d: Expected to fail with error \"%s\", but instead failed with error \"%s\" instead", i+1, testCase.err.Error(), err.Cause.Error())
+			if !strings.Contains(err.Error(), testCase.err.Error()) {
+				t.Errorf("Test %d: Expected to fail with error \"%s\", but instead failed with error \"%s\" instead", i+1, testCase.err.Error(), err.Error())
 			}
 		}
 		// Since there are cases for which ListObjects fails, this is necessary.
@@ -571,21 +567,18 @@ func TestListObjects(t *testing.T) {
 
 func BenchmarkListObjects(b *testing.B) {
 	// Make a temporary directory to use as the obj.
-	directory, e := ioutil.TempDir("", "minio-list-benchmark")
-	if e != nil {
-		b.Fatal(e)
+	directory, err := ioutil.TempDir("", "minio-list-benchmark")
+	if err != nil {
+		b.Fatal(err)
 	}
 	defer os.RemoveAll(directory)
 
 	// Create the obj.
-	fs, e := newFS(directory)
-	if e != nil {
-		b.Fatal(e)
+	obj, err := newFSObjects(directory)
+	if err != nil {
+		b.Fatal(err)
 	}
 
-	obj := newObjectLayer(fs)
-	var err *probe.Error
-
 	// Create a bucket.
 	err = obj.MakeBucket("ls-benchmark-bucket")
 	if err != nil {
diff --git a/object-api-multipart_test.go b/object-api-multipart_test.go
index be0b6e3cd..708921cc0 100644
--- a/object-api-multipart_test.go
+++ b/object-api-multipart_test.go
@@ -21,27 +21,23 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
-	"path"
 	"testing"
 )
 
 // Tests validate creation of new multipart upload instance.
 func TestObjectNewMultipartUpload(t *testing.T) {
-	directory, e := ioutil.TempDir("", "minio-multipart-1-test")
-	if e != nil {
-		t.Fatal(e)
+	directory, err := ioutil.TempDir("", "minio-multipart-1-test")
+	if err != nil {
+		t.Fatal(err)
 	}
 	defer os.RemoveAll(directory)
 
-	// Initialize fs layer.
-	fs, e := newFS(directory)
-	if e != nil {
-		t.Fatal(e)
+	// Initialize fs object layer.
+	obj, err := newFSObjects(directory)
+	if err != nil {
+		t.Fatal(err)
 	}
 
-	// Initialize object layer.
-	obj := newObjectLayer(fs)
-
 	bucket := "minio-bucket"
 	object := "minio-object"
 
@@ -49,77 +45,68 @@ func TestObjectNewMultipartUpload(t *testing.T) {
 	// opearation expected to fail since the bucket on which NewMultipartUpload is being initiated doesn't exist.
 	uploadID, err := obj.NewMultipartUpload(bucket, object)
 	if err == nil {
-		t.Fatalf("Expcected to fail since the NewMultipartUpload is intialized on a non-existant bucket.")
+		t.Fatalf("Expected to fail since the NewMultipartUpload is intialized on a non-existant bucket.")
 	}
-	if errMsg != err.ToGoError().Error() {
-		t.Errorf("Expected to fail with Error \"%s\", but instead found \"%s\".", errMsg, err.ToGoError().Error())
+	if errMsg != err.Error() {
+		t.Errorf("Expected to fail with Error \"%s\", but instead found \"%s\".", errMsg, err.Error())
 	}
 
 	// Create bucket before intiating NewMultipartUpload.
 	err = obj.MakeBucket(bucket)
 	if err != nil {
 		// failed to create newbucket, abort.
-		t.Fatal(err.ToGoError())
+		t.Fatal(err)
 	}
 
 	uploadID, err = obj.NewMultipartUpload(bucket, object)
 	if err != nil {
-		t.Fatal(err.ToGoError())
+		t.Fatal(err)
 	}
 
-	uploadIDPath := path.Join(bucket, object, uploadID)
-	_, e = obj.storage.StatFile(minioMetaVolume, uploadIDPath)
-	if e != nil {
-		if e == errFileNotFound {
+	err = obj.AbortMultipartUpload(bucket, object, uploadID)
+	if err != nil {
+		switch err.(type) {
+		case InvalidUploadID:
 			t.Fatalf("New Multipart upload failed to create uuid file.")
+		default:
+			t.Fatalf(err.Error())
 		}
-		t.Fatalf(e.Error())
 	}
 }
 
 // Tests validates the validator for existence of uploadID.
 func TestObjectAPIIsUploadIDExists(t *testing.T) {
-	directory, e := ioutil.TempDir("", "minio-multipart-2-test")
-	if e != nil {
-		t.Fatal(e)
+	directory, err := ioutil.TempDir("", "minio-multipart-2-test")
+	if err != nil {
+		t.Fatal(err)
 	}
 	defer os.RemoveAll(directory)
 
-	// Initialize fs layer.
-	fs, e := newFS(directory)
-	if e != nil {
-		t.Fatal(e)
+	// Initialize fs object layer.
+	obj, err := newFSObjects(directory)
+	if err != nil {
+		t.Fatal(err)
 	}
 
-	// Initialize object layer.
-	obj := newObjectLayer(fs)
-
 	bucket := "minio-bucket"
 	object := "minio-object"
 
 	// Create bucket before intiating NewMultipartUpload.
-	err := obj.MakeBucket(bucket)
+	err = obj.MakeBucket(bucket)
 	if err != nil {
 		// Failed to create newbucket, abort.
-		t.Fatal(err.ToGoError())
+		t.Fatal(err)
 	}
 
-	// UploadID file shouldn't exist.
-	isExists, e := obj.isUploadIDExists(bucket, object, "abc")
-	if e == nil && isExists {
-		t.Fatal("Expected uploadIDPath to not to exist.")
-	}
-
-	uploadID, err := obj.NewMultipartUpload(bucket, object)
+	_, err = obj.NewMultipartUpload(bucket, object)
 	if err != nil {
-		t.Fatal(err.ToGoError())
+		t.Fatal(err)
 	}
-	// UploadID file should exist.
-	isExists, e = obj.isUploadIDExists(bucket, object, uploadID)
-	if e != nil {
-		t.Fatal(e.Error())
-	}
-	if !isExists {
+
+	err = obj.AbortMultipartUpload(bucket, object, "abc")
+	switch err.(type) {
+	case InvalidUploadID:
+	default:
 		t.Fatal("Expected uploadIDPath to exist.")
 	}
 }
@@ -127,40 +114,38 @@ func TestObjectAPIIsUploadIDExists(t *testing.T) {
 // Tests validate correctness of PutObjectPart.
 func TestObjectAPIPutObjectPart(t *testing.T) {
 	// Generating cases for which the PutObjectPart fails.
-	directory, e := ioutil.TempDir("", "minio-multipart-3-test")
-	if e != nil {
-		t.Fatal(e)
+	directory, err := ioutil.TempDir("", "minio-multipart-3-test")
+	if err != nil {
+		t.Fatal(err)
 	}
 	defer os.RemoveAll(directory)
 
-	// Initializing fs layer.
-	fs, e := newFS(directory)
-	if e != nil {
-		t.Fatal(e)
+	// Initializing fs object layer.
+	obj, err := newFSObjects(directory)
+	if err != nil {
+		t.Fatal(err)
 	}
+
 	bucket := "minio-bucket"
 	object := "minio-object"
 
-	// Initializing object layer.
-	obj := newObjectLayer(fs)
-
 	// Create bucket before intiating NewMultipartUpload.
-	err := obj.MakeBucket(bucket)
+	err = obj.MakeBucket(bucket)
 	if err != nil {
 		// Failed to create newbucket, abort.
-		t.Fatal(err.ToGoError())
+		t.Fatal(err)
 	}
 	// Initiate Multipart Upload on the above created bucket.
 	uploadID, err := obj.NewMultipartUpload(bucket, object)
 	if err != nil {
 		// Failed to create NewMultipartUpload, abort.
-		t.Fatal(err.ToGoError())
+		t.Fatal(err)
 	}
 	// Creating a dummy bucket for tests.
 	err = obj.MakeBucket("unused-bucket")
 	if err != nil {
 		// Failed to create newbucket, abort.
-		t.Fatal(err.ToGoError())
+		t.Fatal(err)
 	}
 
 	failCases := []struct {
@@ -235,31 +220,24 @@ func TestObjectAPIPutObjectPart(t *testing.T) {
 		// All are test cases above are expected to fail.
 
 		if actualErr != nil && testCase.shouldPass {
-			t.Errorf("Test %d: Expected to pass, but failed with: <ERROR> %s.", i+1, actualErr.ToGoError().Error())
+			t.Errorf("Test %d: Expected to pass, but failed with: <ERROR> %s.", i+1, actualErr.Error())
 		}
 		if actualErr == nil && !testCase.shouldPass {
 			t.Errorf("Test %d: Expected to fail with <ERROR> \"%s\", but passed instead.", i+1, testCase.expectedError.Error())
 		}
 		// Failed as expected, but does it fail for the expected reason.
 		if actualErr != nil && !testCase.shouldPass {
-			if testCase.expectedError.Error() != actualErr.ToGoError().Error() {
+			if testCase.expectedError.Error() != actualErr.Error() {
 				t.Errorf("Test %d: Expected to fail with error \"%s\", but instead failed with error \"%s\" instead.", i+1,
-					testCase.expectedError.Error(), actualErr.ToGoError().Error())
+					testCase.expectedError.Error(), actualErr.Error())
 			}
 		}
-		// Since there are cases for which ListObjects fails, this is necessary.
 		// Test passes as expected, but the output values are verified for correctness here.
 		if actualErr == nil && testCase.shouldPass {
 			// Asserting whether the md5 output is correct.
 			if testCase.inputMd5 != actualMd5Hex {
 				t.Errorf("Test %d: Calculated Md5 different from the actual one %s.", i+1, actualMd5Hex)
 			}
-			partSuffix := fmt.Sprintf("%s.%d.%s", uploadID, testCase.PartID, testCase.inputMd5)
-			// Verifying whether the part file is created.
-			_, e := obj.storage.StatFile(minioMetaVolume, path.Join(bucket, object, partSuffix))
-			if e != nil {
-				t.Errorf("Test %d: Failed to create the Part file.", i+1)
-			}
 		}
 	}
 }
diff --git a/object-api_test.go b/object-api_test.go
index 6f4a97756..32678529b 100644
--- a/object-api_test.go
+++ b/object-api_test.go
@@ -29,12 +29,11 @@ var _ = Suite(&MySuite{})
 
 func (s *MySuite) TestFSAPISuite(c *C) {
 	var storageList []string
-	create := func() objectAPI {
+	create := func() ObjectLayer {
 		path, err := ioutil.TempDir(os.TempDir(), "minio-")
 		c.Check(err, IsNil)
-		storageAPI, err := newStorageAPI(path)
+		objAPI, err := newFSObjects(path)
 		c.Check(err, IsNil)
-		objAPI := newObjectLayer(storageAPI)
 		storageList = append(storageList, path)
 		return objAPI
 	}
@@ -48,7 +47,7 @@ func (s *MySuite) TestXLAPISuite(c *C) {
 	// Initialize name space lock.
 	initNSLock()
 
-	create := func() objectAPI {
+	create := func() ObjectLayer {
 		var nDisks = 16 // Maximum disks.
 		var erasureDisks []string
 		for i := 0; i < nDisks; i++ {
@@ -56,10 +55,8 @@ func (s *MySuite) TestXLAPISuite(c *C) {
 			c.Check(err, IsNil)
 			erasureDisks = append(erasureDisks, path)
 		}
-		storageList = append(storageList, erasureDisks...)
-		storageAPI, err := newStorageAPI(erasureDisks...)
+		objAPI, err := newXLObjects(erasureDisks...)
 		c.Check(err, IsNil)
-		objAPI := newObjectLayer(storageAPI)
 		return objAPI
 	}
 	APITestSuite(c, create)
diff --git a/object-handlers.go b/object-handlers.go
index 4eff72d38..93d6f0b0e 100644
--- a/object-handlers.go
+++ b/object-handlers.go
@@ -32,7 +32,6 @@ import (
 	fastSha256 "github.com/minio/minio/pkg/crypto/sha256"
 
 	mux "github.com/gorilla/mux"
-	"github.com/minio/minio/pkg/probe"
 )
 
 // supportedGetReqParams - supported request parameters for GET presigned request.
@@ -100,7 +99,8 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 	// Fetch object stat info.
 	objInfo, err := api.ObjectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
-		switch err.ToGoError().(type) {
+		errorIf(err, "GetObjectInfo failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketNotFound:
@@ -110,7 +110,6 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 		case ObjectNameInvalid:
 			writeErrorResponse(w, r, ErrNoSuchKey, r.URL.Path)
 		default:
-			errorIf(err.Trace(), "GetObjectInfo failed.", nil)
 			writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 		}
 		return
@@ -137,13 +136,13 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 	startOffset := hrange.start
 	readCloser, err := api.ObjectAPI.GetObject(bucket, object, startOffset)
 	if err != nil {
-		switch err.ToGoError().(type) {
+		switch err.(type) {
 		case BucketNotFound:
 			writeErrorResponse(w, r, ErrNoSuchBucket, r.URL.Path)
 		case ObjectNotFound:
 			writeErrorResponse(w, r, errAllowableObjectNotFound(bucket, r), r.URL.Path)
 		default:
-			errorIf(err.Trace(), "GetObject failed.", nil)
+			errorIf(err, "GetObject failed.", nil)
 			writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 		}
 		return
@@ -157,14 +156,14 @@ func (api objectAPIHandlers) GetObjectHandler(w http.ResponseWriter, r *http.Req
 	setGetRespHeaders(w, r.URL.Query())
 
 	if hrange.length > 0 {
-		if _, e := io.CopyN(w, readCloser, hrange.length); e != nil {
-			errorIf(probe.NewError(e), "Writing to client failed", nil)
+		if _, err := io.CopyN(w, readCloser, hrange.length); err != nil {
+			errorIf(err, "Writing to client failed", nil)
 			// Do not send error response here, since client could have died.
 			return
 		}
 	} else {
-		if _, e := io.Copy(w, readCloser); e != nil {
-			errorIf(probe.NewError(e), "Writing to client failed", nil)
+		if _, err := io.Copy(w, readCloser); err != nil {
+			errorIf(err, "Writing to client failed", nil)
 			// Do not send error response here, since client could have died.
 			return
 		}
@@ -294,8 +293,8 @@ func (api objectAPIHandlers) HeadObjectHandler(w http.ResponseWriter, r *http.Re
 
 	objInfo, err := api.ObjectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
-		errorIf(err.Trace(bucket, object), "GetObjectInfo failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "GetObjectInfo failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketNotFound:
@@ -387,8 +386,8 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 
 	objInfo, err := api.ObjectAPI.GetObjectInfo(sourceBucket, sourceObject)
 	if err != nil {
-		errorIf(err.Trace(), "GetObjectInfo failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "GetObjectInfo failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, objectSource)
 		case BucketNotFound:
@@ -425,10 +424,9 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 
 	var md5Bytes []byte
 	if objInfo.MD5Sum != "" {
-		var e error
-		md5Bytes, e = hex.DecodeString(objInfo.MD5Sum)
-		if e != nil {
-			errorIf(probe.NewError(e), "Decoding md5 failed.", nil)
+		md5Bytes, err = hex.DecodeString(objInfo.MD5Sum)
+		if err != nil {
+			errorIf(err, "Decoding md5 failed.", nil)
 			writeErrorResponse(w, r, ErrInvalidDigest, r.URL.Path)
 			return
 		}
@@ -436,10 +434,10 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 
 	startOffset := int64(0) // Read the whole file.
 	// Get the object.
-	readCloser, getErr := api.ObjectAPI.GetObject(sourceBucket, sourceObject, startOffset)
-	if getErr != nil {
-		errorIf(getErr.Trace(sourceBucket, sourceObject), "Reading "+objectSource+" failed.", nil)
-		switch err.ToGoError().(type) {
+	readCloser, err := api.ObjectAPI.GetObject(sourceBucket, sourceObject, startOffset)
+	if err != nil {
+		errorIf(err, "Reading "+objectSource+" failed.", nil)
+		switch err.(type) {
 		case BucketNotFound:
 			writeErrorResponse(w, r, ErrNoSuchBucket, objectSource)
 		case ObjectNotFound:
@@ -459,7 +457,8 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 	// Create the object.
 	md5Sum, err := api.ObjectAPI.PutObject(bucket, object, size, readCloser, metadata)
 	if err != nil {
-		switch err.ToGoError().(type) {
+		errorIf(err, "PutObject failed.", nil)
+		switch err.(type) {
 		case StorageFull:
 			writeErrorResponse(w, r, ErrStorageFull, r.URL.Path)
 		case BucketNotFound:
@@ -473,7 +472,6 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 		case ObjectExistsAsPrefix:
 			writeErrorResponse(w, r, ErrObjectExistsAsPrefix, r.URL.Path)
 		default:
-			errorIf(err.Trace(), "PutObject failed.", nil)
 			writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 		}
 		return
@@ -481,7 +479,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 
 	objInfo, err = api.ObjectAPI.GetObjectInfo(bucket, object)
 	if err != nil {
-		errorIf(err.Trace(), "GetObjectInfo failed.", nil)
+		errorIf(err, "GetObjectInfo failed.", nil)
 		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 		return
 	}
@@ -605,7 +603,7 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 	// Get Content-Md5 sent by client and verify if valid
 	md5Bytes, err := checkValidMD5(r.Header.Get("Content-Md5"))
 	if err != nil {
-		errorIf(err.Trace(r.Header.Get("Content-Md5")), "Decoding md5 failed.", nil)
+		errorIf(err, "Decoding md5 failed.", nil)
 		writeErrorResponse(w, r, ErrInvalidDigest, r.URL.Path)
 		return
 	}
@@ -643,9 +641,9 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 		go func() {
 			shaWriter := fastSha256.New()
 			multiWriter := io.MultiWriter(shaWriter, writer)
-			if _, e := io.CopyN(multiWriter, r.Body, size); e != nil {
-				errorIf(probe.NewError(e), "Unable to read HTTP body.", nil)
-				writer.CloseWithError(e)
+			if _, cerr := io.CopyN(multiWriter, r.Body, size); cerr != nil {
+				errorIf(cerr, "Unable to read HTTP body.", nil)
+				writer.CloseWithError(err)
 				return
 			}
 			shaPayload := shaWriter.Sum(nil)
@@ -676,14 +674,13 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 		md5Sum, err = api.ObjectAPI.PutObject(bucket, object, size, reader, metadata)
 	}
 	if err != nil {
-		errorIf(err.Trace(), "PutObject failed.", nil)
-		e := err.ToGoError()
+		errorIf(err, "PutObject failed.", nil)
 		// Verify if the underlying error is signature mismatch.
-		if e == errSignatureMismatch {
+		if err == errSignatureMismatch {
 			writeErrorResponse(w, r, ErrSignatureDoesNotMatch, r.URL.Path)
 			return
 		}
-		switch e.(type) {
+		switch err.(type) {
 		case StorageFull:
 			writeErrorResponse(w, r, ErrStorageFull, r.URL.Path)
 		case BucketNotFound:
@@ -736,8 +733,8 @@ func (api objectAPIHandlers) NewMultipartUploadHandler(w http.ResponseWriter, r
 
 	uploadID, err := api.ObjectAPI.NewMultipartUpload(bucket, object)
 	if err != nil {
-		errorIf(err.Trace(), "NewMultipartUpload failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "NewMultipartUpload failed.", nil)
+		switch err.(type) {
 		case StorageFull:
 			writeErrorResponse(w, r, ErrStorageFull, r.URL.Path)
 		case BucketNameInvalid:
@@ -771,7 +768,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 	// get Content-Md5 sent by client and verify if valid
 	md5Bytes, err := checkValidMD5(r.Header.Get("Content-Md5"))
 	if err != nil {
-		errorIf(err.Trace(r.Header.Get("Content-Md5")), "Decoding md5 failed.", nil)
+		errorIf(err, "Decoding md5 failed.", nil)
 		writeErrorResponse(w, r, ErrInvalidDigest, r.URL.Path)
 		return
 	}
@@ -792,8 +789,8 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 	uploadID := r.URL.Query().Get("uploadId")
 	partIDString := r.URL.Query().Get("partNumber")
 
-	partID, e := strconv.Atoi(partIDString)
-	if e != nil {
+	partID, err := strconv.Atoi(partIDString)
+	if err != nil {
 		writeErrorResponse(w, r, ErrInvalidPart, r.URL.Path)
 		return
 	}
@@ -822,9 +819,9 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 		go func() {
 			shaWriter := fastSha256.New()
 			multiWriter := io.MultiWriter(shaWriter, writer)
-			if _, e := io.CopyN(multiWriter, r.Body, size); e != nil {
-				errorIf(probe.NewError(e), "Unable to read HTTP body.", nil)
-				writer.CloseWithError(e)
+			if _, err = io.CopyN(multiWriter, r.Body, size); err != nil {
+				errorIf(err, "Unable to read HTTP body.", nil)
+				writer.CloseWithError(err)
 				return
 			}
 			shaPayload := shaWriter.Sum(nil)
@@ -848,14 +845,13 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 		partMD5, err = api.ObjectAPI.PutObjectPart(bucket, object, uploadID, partID, size, reader, hex.EncodeToString(md5Bytes))
 	}
 	if err != nil {
-		errorIf(err.Trace(), "PutObjectPart failed.", nil)
-		e := err.ToGoError()
+		errorIf(err, "PutObjectPart failed.", nil)
 		// Verify if the underlying error is signature mismatch.
-		if e == errSignatureMismatch {
+		if err == errSignatureMismatch {
 			writeErrorResponse(w, r, ErrSignatureDoesNotMatch, r.URL.Path)
 			return
 		}
-		switch e.(type) {
+		switch err.(type) {
 		case StorageFull:
 			writeErrorResponse(w, r, ErrStorageFull, r.URL.Path)
 		case InvalidUploadID:
@@ -900,10 +896,9 @@ func (api objectAPIHandlers) AbortMultipartUploadHandler(w http.ResponseWriter,
 	}
 
 	uploadID, _, _, _ := getObjectResources(r.URL.Query())
-	err := api.ObjectAPI.AbortMultipartUpload(bucket, object, uploadID)
-	if err != nil {
-		errorIf(err.Trace(), "AbortMutlipartUpload failed.", nil)
-		switch err.ToGoError().(type) {
+	if err := api.ObjectAPI.AbortMultipartUpload(bucket, object, uploadID); err != nil {
+		errorIf(err, "AbortMutlipartUpload failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketNotFound:
@@ -961,8 +956,8 @@ func (api objectAPIHandlers) ListObjectPartsHandler(w http.ResponseWriter, r *ht
 
 	listPartsInfo, err := api.ObjectAPI.ListObjectParts(bucket, object, uploadID, partNumberMarker, maxParts)
 	if err != nil {
-		errorIf(err.Trace(), "ListObjectParts failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "ListObjectParts failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketNotFound:
@@ -998,7 +993,7 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 	uploadID, _, _, _ := getObjectResources(r.URL.Query())
 
 	var md5Sum string
-	var err *probe.Error
+	var err error
 	switch getRequestAuthType(r) {
 	default:
 		// For all unknown auth types return error.
@@ -1016,15 +1011,15 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 			return
 		}
 	}
-	completeMultipartBytes, e := ioutil.ReadAll(r.Body)
-	if e != nil {
-		errorIf(probe.NewError(e), "CompleteMultipartUpload failed.", nil)
+	completeMultipartBytes, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		errorIf(err, "CompleteMultipartUpload failed.", nil)
 		writeErrorResponse(w, r, ErrInternalError, r.URL.Path)
 		return
 	}
 	complMultipartUpload := &completeMultipartUpload{}
-	if e = xml.Unmarshal(completeMultipartBytes, complMultipartUpload); e != nil {
-		errorIf(probe.NewError(e), "XML Unmarshal failed", nil)
+	if err = xml.Unmarshal(completeMultipartBytes, complMultipartUpload); err != nil {
+		errorIf(err, "XML Unmarshal failed", nil)
 		writeErrorResponse(w, r, ErrMalformedXML, r.URL.Path)
 		return
 	}
@@ -1042,8 +1037,8 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 	// Complete multipart upload.
 	md5Sum, err = api.ObjectAPI.CompleteMultipartUpload(bucket, object, uploadID, completeParts)
 	if err != nil {
-		errorIf(err.Trace(), "CompleteMultipartUpload failed.", nil)
-		switch err.ToGoError().(type) {
+		errorIf(err, "CompleteMultipartUpload failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketNotFound:
@@ -1099,10 +1094,9 @@ func (api objectAPIHandlers) DeleteObjectHandler(w http.ResponseWriter, r *http.
 			return
 		}
 	}
-	err := api.ObjectAPI.DeleteObject(bucket, object)
-	if err != nil {
-		errorIf(err.Trace(), "DeleteObject failed.", nil)
-		switch err.ToGoError().(type) {
+	if err := api.ObjectAPI.DeleteObject(bucket, object); err != nil {
+		errorIf(err, "DeleteObject failed.", nil)
+		switch err.(type) {
 		case BucketNameInvalid:
 			writeErrorResponse(w, r, ErrInvalidBucketName, r.URL.Path)
 		case BucketNotFound:
diff --git a/object-interface.go b/object-interface.go
new file mode 100644
index 000000000..553b44a5f
--- /dev/null
+++ b/object-interface.go
@@ -0,0 +1,43 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
+
+import "io"
+
+// ObjectLayer implements primitives for object API layer.
+type ObjectLayer interface {
+	// Bucket operations.
+	MakeBucket(bucket string) error
+	GetBucketInfo(bucket string) (bucketInfo BucketInfo, err error)
+	ListBuckets() (buckets []BucketInfo, err error)
+	DeleteBucket(bucket string) error
+	ListObjects(bucket, prefix, marker, delimiter string, maxKeys int) (result ListObjectsInfo, err error)
+
+	// Object operations.
+	GetObject(bucket, object string, startOffset int64) (reader io.ReadCloser, err error)
+	GetObjectInfo(bucket, object string) (objInfo ObjectInfo, err error)
+	PutObject(bucket, object string, size int64, data io.Reader, metadata map[string]string) (md5 string, err error)
+	DeleteObject(bucket, object string) error
+
+	// Multipart operations.
+	ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarker, delimiter string, maxUploads int) (result ListMultipartsInfo, err error)
+	NewMultipartUpload(bucket, object string) (uploadID string, err error)
+	PutObjectPart(bucket, object, uploadID string, partID int, size int64, data io.Reader, md5Hex string) (md5 string, err error)
+	ListObjectParts(bucket, object, uploadID string, partNumberMarker int, maxParts int) (result ListPartsInfo, err error)
+	AbortMultipartUpload(bucket, object, uploadID string) error
+	CompleteMultipartUpload(bucket, object, uploadID string, uploadedParts []completePart) (md5 string, err error)
+}
diff --git a/object-utils.go b/object-utils.go
index 63d3e0627..aa2de285e 100644
--- a/object-utils.go
+++ b/object-utils.go
@@ -17,9 +17,21 @@
 package main
 
 import (
+	"crypto/md5"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
 	"regexp"
 	"strings"
 	"unicode/utf8"
+
+	"github.com/minio/minio/pkg/safe"
+)
+
+const (
+	// Minio meta volume.
+	minioMetaVolume = ".minio"
 )
 
 // validBucket regexp.
@@ -96,3 +108,41 @@ func retainSlash(s string) string {
 func pathJoin(s1 string, s2 string) string {
 	return retainSlash(s1) + s2
 }
+
+// Create an s3 compatible MD5sum for complete multipart transaction.
+func makeS3MD5(md5Strs ...string) (string, error) {
+	var finalMD5Bytes []byte
+	for _, md5Str := range md5Strs {
+		md5Bytes, err := hex.DecodeString(md5Str)
+		if err != nil {
+			return "", err
+		}
+		finalMD5Bytes = append(finalMD5Bytes, md5Bytes...)
+	}
+	md5Hasher := md5.New()
+	md5Hasher.Write(finalMD5Bytes)
+	s3MD5 := fmt.Sprintf("%s-%d", hex.EncodeToString(md5Hasher.Sum(nil)), len(md5Strs))
+	return s3MD5, nil
+}
+
+// byBucketName is a collection satisfying sort.Interface.
+type byBucketName []BucketInfo
+
+func (d byBucketName) Len() int           { return len(d) }
+func (d byBucketName) Swap(i, j int)      { d[i], d[j] = d[j], d[i] }
+func (d byBucketName) Less(i, j int) bool { return d[i].Name < d[j].Name }
+
+// safeCloseAndRemove - safely closes and removes underlying temporary
+// file writer if possible.
+func safeCloseAndRemove(writer io.WriteCloser) error {
+	// If writer is a safe file, Attempt to close and remove.
+	safeWriter, ok := writer.(*safe.File)
+	if ok {
+		return safeWriter.CloseAndRemove()
+	}
+	pipeWriter, ok := writer.(*io.PipeWriter)
+	if ok {
+		return pipeWriter.CloseWithError(errors.New("Close and error out."))
+	}
+	return nil
+}
diff --git a/object_api_suite_test.go b/object_api_suite_test.go
index a322c0e61..75e256550 100644
--- a/object_api_suite_test.go
+++ b/object_api_suite_test.go
@@ -31,7 +31,7 @@ import (
 // TODO - enable all the commented tests.
 
 // APITestSuite - collection of API tests.
-func APITestSuite(c *check.C, create func() objectAPI) {
+func APITestSuite(c *check.C, create func() ObjectLayer) {
 	testMakeBucket(c, create)
 	testMultipleObjectCreation(c, create)
 	testPaging(c, create)
@@ -50,7 +50,7 @@ func APITestSuite(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate bucket creation.
-func testMakeBucket(c *check.C, create func() objectAPI) {
+func testMakeBucket(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("bucket-unknown")
 	c.Assert(err, check.IsNil)
@@ -58,7 +58,7 @@ func testMakeBucket(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate creation of part files during Multipart operation.
-func testMultipartObjectCreation(c *check.C, create func() objectAPI) {
+func testMultipartObjectCreation(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("bucket")
 	c.Assert(err, check.IsNil)
@@ -83,7 +83,7 @@ func testMultipartObjectCreation(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate abortion of Multipart operation.
-func testMultipartObjectAbort(c *check.C, create func() objectAPI) {
+func testMultipartObjectAbort(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("bucket")
 	c.Assert(err, check.IsNil)
@@ -115,7 +115,7 @@ func testMultipartObjectAbort(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate object creation.
-func testMultipleObjectCreation(c *check.C, create func() objectAPI) {
+func testMultipleObjectCreation(c *check.C, create func() ObjectLayer) {
 	objects := make(map[string][]byte)
 	obj := create()
 	err := obj.MakeBucket("bucket")
@@ -157,7 +157,7 @@ func testMultipleObjectCreation(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate creation of objects and the order of listing using various filters for ListObjects operation.
-func testPaging(c *check.C, create func() objectAPI) {
+func testPaging(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	obj.MakeBucket("bucket")
 	result, err := obj.ListObjects("bucket", "", "", "", 0)
@@ -261,7 +261,7 @@ func testPaging(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate overwriting of an existing object.
-func testObjectOverwriteWorks(c *check.C, create func() objectAPI) {
+func testObjectOverwriteWorks(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("bucket")
 	c.Assert(err, check.IsNil)
@@ -284,25 +284,25 @@ func testObjectOverwriteWorks(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate that bucket operation on non-existent bucket fails.
-func testNonExistantBucketOperations(c *check.C, create func() objectAPI) {
+func testNonExistantBucketOperations(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	_, err := obj.PutObject("bucket1", "object", int64(len("one")), bytes.NewBufferString("one"), nil)
 	c.Assert(err, check.Not(check.IsNil))
-	c.Assert(err.ToGoError().Error(), check.Equals, "Bucket not found: bucket1")
+	c.Assert(err.Error(), check.Equals, "Bucket not found: bucket1")
 }
 
 // Tests validate that recreation of the bucket fails.
-func testBucketRecreateFails(c *check.C, create func() objectAPI) {
+func testBucketRecreateFails(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("string")
 	c.Assert(err, check.IsNil)
 	err = obj.MakeBucket("string")
 	c.Assert(err, check.Not(check.IsNil))
-	c.Assert(err.ToGoError().Error(), check.Equals, "Bucket exists: string")
+	c.Assert(err.Error(), check.Equals, "Bucket exists: string")
 }
 
 // Tests validate PutObject with subdirectory prefix.
-func testPutObjectInSubdir(c *check.C, create func() objectAPI) {
+func testPutObjectInSubdir(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("bucket")
 	c.Assert(err, check.IsNil)
@@ -321,7 +321,7 @@ func testPutObjectInSubdir(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate ListBuckets.
-func testListBuckets(c *check.C, create func() objectAPI) {
+func testListBuckets(c *check.C, create func() ObjectLayer) {
 	obj := create()
 
 	// test empty list.
@@ -354,7 +354,7 @@ func testListBuckets(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate the order of result of ListBuckets.
-func testListBucketsOrder(c *check.C, create func() objectAPI) {
+func testListBucketsOrder(c *check.C, create func() ObjectLayer) {
 	// if implementation contains a map, order of map keys will vary.
 	// this ensures they return in the same order each time.
 	for i := 0; i < 10; i++ {
@@ -373,24 +373,24 @@ func testListBucketsOrder(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate that ListObjects operation on a non-existent bucket fails as expected.
-func testListObjectsTestsForNonExistantBucket(c *check.C, create func() objectAPI) {
+func testListObjectsTestsForNonExistantBucket(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	result, err := obj.ListObjects("bucket", "", "", "", 1000)
 	c.Assert(err, check.Not(check.IsNil))
 	c.Assert(result.IsTruncated, check.Equals, false)
 	c.Assert(len(result.Objects), check.Equals, 0)
-	c.Assert(err.ToGoError().Error(), check.Equals, "Bucket not found: bucket")
+	c.Assert(err.Error(), check.Equals, "Bucket not found: bucket")
 }
 
 // Tests validate that GetObject fails on a non-existent bucket as expected.
-func testNonExistantObjectInBucket(c *check.C, create func() objectAPI) {
+func testNonExistantObjectInBucket(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("bucket")
 	c.Assert(err, check.IsNil)
 
 	_, err = obj.GetObject("bucket", "dir1", 0)
 	c.Assert(err, check.Not(check.IsNil))
-	switch err := err.ToGoError().(type) {
+	switch err := err.(type) {
 	case ObjectNotFound:
 		c.Assert(err, check.ErrorMatches, "Object not found: bucket#dir1")
 	default:
@@ -399,7 +399,7 @@ func testNonExistantObjectInBucket(c *check.C, create func() objectAPI) {
 }
 
 // Tests validate that GetObject on an existing directory fails as expected.
-func testGetDirectoryReturnsObjectNotFound(c *check.C, create func() objectAPI) {
+func testGetDirectoryReturnsObjectNotFound(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("bucket")
 	c.Assert(err, check.IsNil)
@@ -408,7 +408,7 @@ func testGetDirectoryReturnsObjectNotFound(c *check.C, create func() objectAPI)
 	c.Assert(err, check.IsNil)
 
 	_, err = obj.GetObject("bucket", "dir1", 0)
-	switch err := err.ToGoError().(type) {
+	switch err := err.(type) {
 	case ObjectNotFound:
 		c.Assert(err.Bucket, check.Equals, "bucket")
 		c.Assert(err.Object, check.Equals, "dir1")
@@ -418,7 +418,7 @@ func testGetDirectoryReturnsObjectNotFound(c *check.C, create func() objectAPI)
 	}
 
 	_, err = obj.GetObject("bucket", "dir1/", 0)
-	switch err := err.ToGoError().(type) {
+	switch err := err.(type) {
 	case ObjectNotFound:
 		c.Assert(err.Bucket, check.Equals, "bucket")
 		c.Assert(err.Object, check.Equals, "dir1/")
@@ -429,7 +429,7 @@ func testGetDirectoryReturnsObjectNotFound(c *check.C, create func() objectAPI)
 }
 
 // Tests valdiate the default ContentType.
-func testDefaultContentType(c *check.C, create func() objectAPI) {
+func testDefaultContentType(c *check.C, create func() ObjectLayer) {
 	obj := create()
 	err := obj.MakeBucket("bucket")
 	c.Assert(err, check.IsNil)
diff --git a/pkg/quick/quick.go b/pkg/quick/quick.go
index 1ef27f755..691dca569 100644
--- a/pkg/quick/quick.go
+++ b/pkg/quick/quick.go
@@ -30,7 +30,6 @@ import (
 	"sync"
 
 	"github.com/fatih/structs"
-	"github.com/minio/minio/pkg/probe"
 	"github.com/minio/minio/pkg/safe"
 )
 
@@ -38,11 +37,11 @@ import (
 type Config interface {
 	String() string
 	Version() string
-	Save(string) *probe.Error
-	Load(string) *probe.Error
+	Save(string) error
+	Load(string) error
 	Data() interface{}
-	Diff(Config) ([]structs.Field, *probe.Error)
-	DeepDiff(Config) ([]structs.Field, *probe.Error)
+	Diff(Config) ([]structs.Field, error)
+	DeepDiff(Config) ([]structs.Field, error)
 }
 
 // config - implements quick.Config interface
@@ -53,28 +52,28 @@ type config struct {
 
 // CheckData - checks the validity of config data. Data should be of
 // type struct and contain a string type field called "Version".
-func CheckData(data interface{}) *probe.Error {
+func CheckData(data interface{}) error {
 	if !structs.IsStruct(data) {
-		return probe.NewError(fmt.Errorf("Invalid argument type. Expecing \"struct\" type."))
+		return fmt.Errorf("Invalid argument type. Expecing \"struct\" type.")
 	}
 
 	st := structs.New(data)
 	f, ok := st.FieldOk("Version")
 	if !ok {
-		return probe.NewError(fmt.Errorf("Invalid type of struct argument. No [%s.Version] field found.", st.Name()))
+		return fmt.Errorf("Invalid type of struct argument. No [%s.Version] field found.", st.Name())
 	}
 
 	if f.Kind() != reflect.String {
-		return probe.NewError(fmt.Errorf("Invalid type of struct argument. Expecting \"string\" type [%s.Version] field.", st.Name()))
+		return fmt.Errorf("Invalid type of struct argument. Expecting \"string\" type [%s.Version] field.", st.Name())
 	}
 
 	return nil
 }
 
 // New - instantiate a new config
-func New(data interface{}) (Config, *probe.Error) {
+func New(data interface{}) (Config, error) {
 	if err := CheckData(data); err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 
 	d := new(config)
@@ -85,15 +84,15 @@ func New(data interface{}) (Config, *probe.Error) {
 
 // CheckVersion - loads json and compares the version number provided returns back true or false - any failure
 // is returned as error.
-func CheckVersion(filename string, version string) (bool, *probe.Error) {
-	_, e := os.Stat(filename)
-	if e != nil {
-		return false, probe.NewError(e)
+func CheckVersion(filename string, version string) (bool, error) {
+	_, err := os.Stat(filename)
+	if err != nil {
+		return false, err
 	}
 
-	fileData, e := ioutil.ReadFile(filename)
-	if e != nil {
-		return false, probe.NewError(e)
+	fileData, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return false, err
 	}
 
 	if runtime.GOOS == "windows" {
@@ -104,18 +103,18 @@ func CheckVersion(filename string, version string) (bool, *probe.Error) {
 	}{
 		Version: "",
 	}
-	e = json.Unmarshal(fileData, &data)
-	if e != nil {
-		switch e := e.(type) {
+	err = json.Unmarshal(fileData, &data)
+	if err != nil {
+		switch err := err.(type) {
 		case *json.SyntaxError:
-			return false, probe.NewError(FormatJSONSyntaxError(bytes.NewReader(fileData), e))
+			return false, FormatJSONSyntaxError(bytes.NewReader(fileData), err)
 		default:
-			return false, probe.NewError(e)
+			return false, err
 		}
 	}
 	config, err := New(data)
 	if err != nil {
-		return false, err.Trace()
+		return false, err
 	}
 	if config.Version() != version {
 		return false, nil
@@ -124,34 +123,34 @@ func CheckVersion(filename string, version string) (bool, *probe.Error) {
 }
 
 // Load - loads json config from filename for the a given struct data
-func Load(filename string, data interface{}) (Config, *probe.Error) {
-	_, e := os.Stat(filename)
-	if e != nil {
-		return nil, probe.NewError(e)
+func Load(filename string, data interface{}) (Config, error) {
+	_, err := os.Stat(filename)
+	if err != nil {
+		return nil, err
 	}
 
-	fileData, e := ioutil.ReadFile(filename)
-	if e != nil {
-		return nil, probe.NewError(e)
+	fileData, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
 	}
 
 	if runtime.GOOS == "windows" {
 		fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
 	}
 
-	e = json.Unmarshal(fileData, &data)
-	if e != nil {
-		switch e := e.(type) {
+	err = json.Unmarshal(fileData, &data)
+	if err != nil {
+		switch err := err.(type) {
 		case *json.SyntaxError:
-			return nil, probe.NewError(FormatJSONSyntaxError(bytes.NewReader(fileData), e))
+			return nil, FormatJSONSyntaxError(bytes.NewReader(fileData), err)
 		default:
-			return nil, probe.NewError(e)
+			return nil, err
 		}
 	}
 
 	config, err := New(data)
 	if err != nil {
-		return nil, err.Trace()
+		return nil, err
 	}
 
 	return config, nil
@@ -177,20 +176,16 @@ func (d config) Version() string {
 // writeFile writes data to a file named by filename.
 // If the file does not exist, writeFile creates it;
 // otherwise writeFile truncates it before writing.
-func writeFile(filename string, data []byte) *probe.Error {
-	safeFile, e := safe.CreateFile(filename)
-	if e != nil {
-		return probe.NewError(e)
+func writeFile(filename string, data []byte) error {
+	safeFile, err := safe.CreateFile(filename)
+	if err != nil {
+		return err
 	}
-	_, e = safeFile.Write(data)
-	if e != nil {
-		return probe.NewError(e)
+	_, err = safeFile.Write(data)
+	if err != nil {
+		return err
 	}
-	e = safeFile.Close()
-	if e != nil {
-		return probe.NewError(e)
-	}
-	return nil
+	return safeFile.Close()
 }
 
 // String converts JSON config to printable string
@@ -200,37 +195,37 @@ func (d config) String() string {
 }
 
 // Save writes config data in JSON format to a file.
-func (d config) Save(filename string) *probe.Error {
+func (d config) Save(filename string) error {
 	d.lock.Lock()
 	defer d.lock.Unlock()
 
 	// Check for existing file, if yes create a backup.
-	st, e := os.Stat(filename)
+	st, err := os.Stat(filename)
 	// If file exists and stat failed return here.
-	if e != nil && !os.IsNotExist(e) {
-		return probe.NewError(e)
+	if err != nil && !os.IsNotExist(err) {
+		return err
 	}
 	// File exists and proceed to take backup.
-	if e == nil {
+	if err == nil {
 		// File exists and is not a regular file return error.
 		if !st.Mode().IsRegular() {
-			return probe.NewError(fmt.Errorf("%s is not a regular file", filename))
+			return fmt.Errorf("%s is not a regular file", filename)
 		}
 		// Read old data.
 		var oldData []byte
-		oldData, e = ioutil.ReadFile(filename)
-		if e != nil {
-			return probe.NewError(e)
+		oldData, err = ioutil.ReadFile(filename)
+		if err != nil {
+			return err
 		}
 		// Save read data to the backup file.
-		if err := writeFile(filename+".old", oldData); err != nil {
-			return err.Trace(filename + ".old")
+		if err = writeFile(filename+".old", oldData); err != nil {
+			return err
 		}
 	}
 	// Proceed to create or overwrite file.
-	jsonData, e := json.MarshalIndent(d.data, "", "\t")
-	if e != nil {
-		return probe.NewError(e)
+	jsonData, err := json.MarshalIndent(d.data, "", "\t")
+	if err != nil {
+		return err
 	}
 
 	if runtime.GOOS == "windows" {
@@ -238,23 +233,22 @@ func (d config) Save(filename string) *probe.Error {
 	}
 
 	// Save data.
-	err := writeFile(filename, jsonData)
-	return err.Trace(filename)
+	return writeFile(filename, jsonData)
 }
 
 // Load - loads JSON config from file and merge with currently set values
-func (d *config) Load(filename string) *probe.Error {
+func (d *config) Load(filename string) error {
 	d.lock.Lock()
 	defer d.lock.Unlock()
 
-	_, e := os.Stat(filename)
-	if e != nil {
-		return probe.NewError(e)
+	_, err := os.Stat(filename)
+	if err != nil {
+		return err
 	}
 
-	fileData, e := ioutil.ReadFile(filename)
-	if e != nil {
-		return probe.NewError(e)
+	fileData, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return err
 	}
 
 	if runtime.GOOS == "windows" {
@@ -264,25 +258,25 @@ func (d *config) Load(filename string) *probe.Error {
 	st := structs.New(d.data)
 	f, ok := st.FieldOk("Version")
 	if !ok {
-		return probe.NewError(fmt.Errorf("Argument struct [%s] does not contain field \"Version\".", st.Name()))
+		return fmt.Errorf("Argument struct [%s] does not contain field \"Version\".", st.Name())
 	}
 
-	e = json.Unmarshal(fileData, d.data)
-	if e != nil {
-		switch e := e.(type) {
+	err = json.Unmarshal(fileData, d.data)
+	if err != nil {
+		switch err := err.(type) {
 		case *json.SyntaxError:
-			return probe.NewError(FormatJSONSyntaxError(bytes.NewReader(fileData), e))
+			return FormatJSONSyntaxError(bytes.NewReader(fileData), err)
 		default:
-			return probe.NewError(e)
+			return err
 		}
 	}
 
 	if err := CheckData(d.data); err != nil {
-		return err.Trace(filename)
+		return err
 	}
 
 	if (*d).Version() != f.Value() {
-		return probe.NewError(fmt.Errorf("Version mismatch"))
+		return fmt.Errorf("Version mismatch")
 	}
 
 	return nil
@@ -294,11 +288,11 @@ func (d config) Data() interface{} {
 }
 
 //Diff  - list fields that are in A but not in B
-func (d config) Diff(c Config) ([]structs.Field, *probe.Error) {
+func (d config) Diff(c Config) ([]structs.Field, error) {
 	var fields []structs.Field
 	err := CheckData(c.Data())
 	if err != nil {
-		return []structs.Field{}, err.Trace()
+		return []structs.Field{}, err
 	}
 
 	currFields := structs.Fields(d.Data())
@@ -320,11 +314,11 @@ func (d config) Diff(c Config) ([]structs.Field, *probe.Error) {
 }
 
 //DeepDiff  - list fields in A that are missing or not equal to fields in B
-func (d config) DeepDiff(c Config) ([]structs.Field, *probe.Error) {
+func (d config) DeepDiff(c Config) ([]structs.Field, error) {
 	var fields []structs.Field
 	err := CheckData(c.Data())
 	if err != nil {
-		return []structs.Field{}, err.Trace()
+		return []structs.Field{}, err
 	}
 
 	currFields := structs.Fields(d.Data())
diff --git a/fs-dir-common.go b/posix-dir-common.go
similarity index 100%
rename from fs-dir-common.go
rename to posix-dir-common.go
diff --git a/fs-dir-nix.go b/posix-dir-nix.go
similarity index 100%
rename from fs-dir-nix.go
rename to posix-dir-nix.go
diff --git a/fs-dir-others.go b/posix-dir-others.go
similarity index 100%
rename from fs-dir-others.go
rename to posix-dir-others.go
diff --git a/fs-dirent-fileno.go b/posix-dirent-fileno.go
similarity index 100%
rename from fs-dirent-fileno.go
rename to posix-dirent-fileno.go
diff --git a/fs-dirent-ino.go b/posix-dirent-ino.go
similarity index 100%
rename from fs-dirent-ino.go
rename to posix-dirent-ino.go
diff --git a/fs-utils.go b/posix-utils.go
similarity index 100%
rename from fs-utils.go
rename to posix-utils.go
diff --git a/fs.go b/posix.go
similarity index 99%
rename from fs.go
rename to posix.go
index 1a9cadb96..e1628d53f 100644
--- a/fs.go
+++ b/posix.go
@@ -78,7 +78,7 @@ func isDirExist(dirname string) (bool, error) {
 }
 
 // Initialize a new storage disk.
-func newFS(diskPath string) (StorageAPI, error) {
+func newPosix(diskPath string) (StorageAPI, error) {
 	if diskPath == "" {
 		log.Debug("Disk cannot be empty")
 		return nil, errInvalidArgument
diff --git a/routers.go b/routers.go
index 6a9e6f73a..39afda7f7 100644
--- a/routers.go
+++ b/routers.go
@@ -18,38 +18,30 @@ package main
 
 import (
 	"net/http"
-	"path/filepath"
-	"strings"
 
 	router "github.com/gorilla/mux"
-	"github.com/minio/minio/pkg/probe"
 )
 
-// newStorageAPI - initialize any storage API depending on the export path style.
-func newStorageAPI(exportPaths ...string) (StorageAPI, error) {
+// newObjectLayer - initialize any object layer depending on the
+// number of export paths.
+func newObjectLayer(exportPaths ...string) (ObjectLayer, error) {
 	if len(exportPaths) == 1 {
 		exportPath := exportPaths[0]
-		if !strings.ContainsRune(exportPath, ':') || filepath.VolumeName(exportPath) != "" {
-			// Initialize filesystem storage API.
-			return newFS(exportPath)
-		}
-		// Initialize network storage API.
-		return newNetworkFS(exportPath)
+		// Initialize FS object layer.
+		return newFSObjects(exportPath)
 	}
-	// Initialize XL storage API.
-	return newXL(exportPaths...)
+	// Initialize XL object layer.
+	return newXLObjects(exportPaths...)
 }
 
 // configureServer handler returns final handler for the http server.
 func configureServerHandler(srvCmdConfig serverCmdConfig) http.Handler {
-	storageAPI, e := newStorageAPI(srvCmdConfig.exportPaths...)
-	fatalIf(probe.NewError(e), "Initializing storage API failed.", nil)
+	objAPI, err := newObjectLayer(srvCmdConfig.exportPaths...)
+	fatalIf(err, "Initializing object layer failed.", nil)
 
-	// Initialize object layer.
-	objAPI := newObjectLayer(storageAPI)
-
-	// Initialize storage rpc.
-	storageRPC := newStorageRPC(storageAPI)
+	// Initialize storage rpc server.
+	storageRPC, err := newRPCServer(srvCmdConfig.exportPaths[0]) // FIXME: should only have one path.
+	fatalIf(err, "Initializing storage rpc server failed.", nil)
 
 	// Initialize API.
 	apiHandlers := objectAPIHandlers{
diff --git a/network-fs.go b/rpc-client.go
similarity index 98%
rename from network-fs.go
rename to rpc-client.go
index 7c5dca2b5..5f9904e39 100644
--- a/network-fs.go
+++ b/rpc-client.go
@@ -76,8 +76,8 @@ func toStorageErr(err error) error {
 	return err
 }
 
-// Initialize new network file system.
-func newNetworkFS(networkPath string) (StorageAPI, error) {
+// Initialize new rpc client.
+func newRPCClient(networkPath string) (StorageAPI, error) {
 	// Input validation.
 	if networkPath == "" || strings.LastIndex(networkPath, ":") == -1 {
 		log.WithFields(logrus.Fields{
diff --git a/storage-rpc-datatypes.go b/rpc-server-datatypes.go
similarity index 100%
rename from storage-rpc-datatypes.go
rename to rpc-server-datatypes.go
diff --git a/storage-rpc-server.go b/rpc-server.go
similarity index 96%
rename from storage-rpc-server.go
rename to rpc-server.go
index 3329924be..4d1f05d74 100644
--- a/storage-rpc-server.go
+++ b/rpc-server.go
@@ -119,10 +119,15 @@ func (s *storageServer) DeleteFileHandler(arg *DeleteFileArgs, reply *GenericRep
 }
 
 // Initialize new storage rpc.
-func newStorageRPC(storageAPI StorageAPI) *storageServer {
-	return &storageServer{
-		storage: storageAPI,
+func newRPCServer(exportPath string) (*storageServer, error) {
+	// Initialize posix storage API.
+	storage, err := newPosix(exportPath)
+	if err != nil {
+		return nil, err
 	}
+	return &storageServer{
+		storage: storage,
+	}, nil
 }
 
 // registerStorageRPCRouter - register storage rpc router.
diff --git a/server-main.go b/server-main.go
index 028087606..4f5d63771 100644
--- a/server-main.go
+++ b/server-main.go
@@ -31,7 +31,6 @@ import (
 	"github.com/minio/cli"
 	"github.com/minio/mc/pkg/console"
 	"github.com/minio/minio/pkg/minhttp"
-	"github.com/minio/minio/pkg/probe"
 )
 
 var serverCmd = cli.Command{
@@ -89,11 +88,11 @@ func configureServer(srvCmdConfig serverCmdConfig) *http.Server {
 
 	// Configure TLS if certs are available.
 	if isSSL() {
-		var e error
+		var err error
 		apiServer.TLSConfig = &tls.Config{}
 		apiServer.TLSConfig.Certificates = make([]tls.Certificate, 1)
-		apiServer.TLSConfig.Certificates[0], e = tls.LoadX509KeyPair(mustGetCertFile(), mustGetKeyFile())
-		fatalIf(probe.NewError(e), "Unable to load certificates.", nil)
+		apiServer.TLSConfig.Certificates[0], err = tls.LoadX509KeyPair(mustGetCertFile(), mustGetKeyFile())
+		fatalIf(err, "Unable to load certificates.", nil)
 	}
 
 	// Returns configured HTTP server.
@@ -102,16 +101,16 @@ func configureServer(srvCmdConfig serverCmdConfig) *http.Server {
 
 // Print listen ips.
 func printListenIPs(httpServerConf *http.Server) {
-	host, port, e := net.SplitHostPort(httpServerConf.Addr)
-	fatalIf(probe.NewError(e), "Unable to split host port.", nil)
+	host, port, err := net.SplitHostPort(httpServerConf.Addr)
+	fatalIf(err, "Unable to split host port.", nil)
 
 	var hosts []string
 	switch {
 	case host != "":
 		hosts = append(hosts, host)
 	default:
-		addrs, e := net.InterfaceAddrs()
-		fatalIf(probe.NewError(e), "Unable to get interface address.", nil)
+		addrs, err := net.InterfaceAddrs()
+		fatalIf(err, "Unable to get interface address.", nil)
 		for _, addr := range addrs {
 			if addr.Network() == "ip+net" {
 				host := strings.Split(addr.String(), "/")[0]
@@ -134,7 +133,7 @@ func printListenIPs(httpServerConf *http.Server) {
 func initServerConfig(c *cli.Context) {
 	// Save new config.
 	err := serverConfig.Save()
-	fatalIf(err.Trace(), "Unable to save config.", nil)
+	fatalIf(err, "Unable to save config.", nil)
 
 	// Fetch access keys from environment variables if any and update the config.
 	accessKey := os.Getenv("MINIO_ACCESS_KEY")
@@ -143,10 +142,10 @@ func initServerConfig(c *cli.Context) {
 	// Validate if both keys are specified and they are valid save them.
 	if accessKey != "" && secretKey != "" {
 		if !isValidAccessKey.MatchString(accessKey) {
-			fatalIf(probe.NewError(errInvalidArgument), "Access key does not have required length", nil)
+			fatalIf(errInvalidArgument, "Access key does not have required length", nil)
 		}
 		if !isValidSecretKey.MatchString(secretKey) {
-			fatalIf(probe.NewError(errInvalidArgument), "Secret key does not have required length", nil)
+			fatalIf(errInvalidArgument, "Secret key does not have required length", nil)
 		}
 		serverConfig.SetCredential(credential{
 			AccessKeyID:     accessKey,
@@ -169,10 +168,10 @@ func checkServerSyntax(c *cli.Context) {
 
 // Extract port number from address address should be of the form host:port.
 func getPort(address string) int {
-	_, portStr, e := net.SplitHostPort(address)
-	fatalIf(probe.NewError(e), "Unable to split host port.", nil)
-	portInt, e := strconv.Atoi(portStr)
-	fatalIf(probe.NewError(e), "Invalid port number.", nil)
+	_, portStr, err := net.SplitHostPort(address)
+	fatalIf(err, "Unable to split host port.", nil)
+	portInt, err := strconv.Atoi(portStr)
+	fatalIf(err, "Invalid port number.", nil)
 	return portInt
 }
 
@@ -186,11 +185,11 @@ func getPort(address string) int {
 // on 127.0.0.1 even though minio server is running. So before we start
 // the minio server we make sure that the port is free on all the IPs.
 func checkPortAvailability(port int) {
-	isAddrInUse := func(e error) bool {
+	isAddrInUse := func(err error) bool {
 		// Check if the syscall error is EADDRINUSE.
 		// EADDRINUSE is the system call error if another process is
 		// already listening at the specified port.
-		neterr, ok := e.(*net.OpError)
+		neterr, ok := err.(*net.OpError)
 		if !ok {
 			return false
 		}
@@ -207,19 +206,19 @@ func checkPortAvailability(port int) {
 		}
 		return true
 	}
-	ifcs, e := net.Interfaces()
-	if e != nil {
-		fatalIf(probe.NewError(e), "Unable to list interfaces.", nil)
+	ifcs, err := net.Interfaces()
+	if err != nil {
+		fatalIf(err, "Unable to list interfaces.", nil)
 	}
 	for _, ifc := range ifcs {
-		addrs, e := ifc.Addrs()
-		if e != nil {
-			fatalIf(probe.NewError(e), fmt.Sprintf("Unable to list addresses on interface %s.", ifc.Name), nil)
+		addrs, err := ifc.Addrs()
+		if err != nil {
+			fatalIf(err, fmt.Sprintf("Unable to list addresses on interface %s.", ifc.Name), nil)
 		}
 		for _, addr := range addrs {
 			ipnet, ok := addr.(*net.IPNet)
 			if !ok {
-				errorIf(probe.NewError(errors.New("")), "Interface type assertion to (*net.IPNet) failed.", nil)
+				errorIf(errors.New(""), "Interface type assertion to (*net.IPNet) failed.", nil)
 				continue
 			}
 			ip := ipnet.IP
@@ -228,19 +227,18 @@ func checkPortAvailability(port int) {
 				network = "tcp6"
 			}
 			tcpAddr := net.TCPAddr{IP: ip, Port: port, Zone: ifc.Name}
-			l, e := net.ListenTCP(network, &tcpAddr)
-			if e != nil {
-				if isAddrInUse(e) {
+			l, err := net.ListenTCP(network, &tcpAddr)
+			if err != nil {
+				if isAddrInUse(err) {
 					// Fail if port is already in use.
-					fatalIf(probe.NewError(e), fmt.Sprintf("Unable to listen on IP %s, port %.d", tcpAddr.IP, tcpAddr.Port), nil)
+					fatalIf(err, fmt.Sprintf("Unable to listen on IP %s, port %.d", tcpAddr.IP, tcpAddr.Port), nil)
 				} else {
 					// Ignore other errors.
 					continue
 				}
 			}
-			e = l.Close()
-			if e != nil {
-				fatalIf(probe.NewError(e), fmt.Sprintf("Unable to close listener on IP %s, port %.d", tcpAddr.IP, tcpAddr.Port), nil)
+			if err = l.Close(); err != nil {
+				fatalIf(err, fmt.Sprintf("Unable to close listener on IP %s, port %.d", tcpAddr.IP, tcpAddr.Port), nil)
 			}
 		}
 	}
@@ -308,5 +306,5 @@ func serverMain(c *cli.Context) {
 
 	// Start server.
 	err := minhttp.ListenAndServe(apiServer)
-	errorIf(err.Trace(), "Failed to start the minio server.", nil)
+	errorIf(err.Cause, "Failed to start the minio server.", nil)
 }
diff --git a/signature-jwt.go b/signature-jwt.go
index 7d7336921..932174465 100644
--- a/signature-jwt.go
+++ b/signature-jwt.go
@@ -21,7 +21,6 @@ import (
 	"time"
 
 	jwtgo "github.com/dgrijalva/jwt-go"
-	"github.com/minio/minio/pkg/probe"
 	"golang.org/x/crypto/bcrypt"
 )
 
@@ -49,17 +48,13 @@ func initJWT() *JWT {
 }
 
 // GenerateToken - generates a new Json Web Token based on the incoming user id.
-func (jwt *JWT) GenerateToken(userName string) (string, *probe.Error) {
+func (jwt *JWT) GenerateToken(userName string) (string, error) {
 	token := jwtgo.New(jwtgo.SigningMethodHS512)
 	// Token expires in 10hrs.
 	token.Claims["exp"] = time.Now().Add(time.Hour * tokenExpires).Unix()
 	token.Claims["iat"] = time.Now().Unix()
 	token.Claims["sub"] = userName
-	tokenString, e := token.SignedString([]byte(jwt.SecretAccessKey))
-	if e != nil {
-		return "", probe.NewError(e)
-	}
-	return tokenString, nil
+	return token.SignedString([]byte(jwt.SecretAccessKey))
 }
 
 // Authenticate - authenticates incoming username and password.
diff --git a/signature-v4-postpolicyform.go b/signature-v4-postpolicyform.go
index 20ea45dc7..0abf54d6b 100644
--- a/signature-v4-postpolicyform.go
+++ b/signature-v4-postpolicyform.go
@@ -23,8 +23,6 @@ import (
 	"reflect"
 	"strings"
 	"time"
-
-	"github.com/minio/minio/pkg/probe"
 )
 
 // toString - Safely convert interface to string without causing panic.
@@ -70,7 +68,7 @@ type PostPolicyForm struct {
 }
 
 // parsePostPolicyFormV4 - Parse JSON policy string into typed POostPolicyForm structure.
-func parsePostPolicyFormV4(policy string) (PostPolicyForm, *probe.Error) {
+func parsePostPolicyFormV4(policy string) (PostPolicyForm, error) {
 	// Convert po into interfaces and
 	// perform strict type conversion using reflection.
 	var rawPolicy struct {
@@ -78,17 +76,17 @@ func parsePostPolicyFormV4(policy string) (PostPolicyForm, *probe.Error) {
 		Conditions []interface{} `json:"conditions"`
 	}
 
-	e := json.Unmarshal([]byte(policy), &rawPolicy)
-	if e != nil {
-		return PostPolicyForm{}, probe.NewError(e)
+	err := json.Unmarshal([]byte(policy), &rawPolicy)
+	if err != nil {
+		return PostPolicyForm{}, err
 	}
 
 	parsedPolicy := PostPolicyForm{}
 
 	// Parse expiry time.
-	parsedPolicy.Expiration, e = time.Parse(time.RFC3339Nano, rawPolicy.Expiration)
-	if e != nil {
-		return PostPolicyForm{}, probe.NewError(e)
+	parsedPolicy.Expiration, err = time.Parse(time.RFC3339Nano, rawPolicy.Expiration)
+	if err != nil {
+		return PostPolicyForm{}, err
 	}
 	parsedPolicy.Conditions.Policies = make(map[string]struct {
 		Operator string
@@ -102,8 +100,7 @@ func parsePostPolicyFormV4(policy string) (PostPolicyForm, *probe.Error) {
 			for k, v := range condt {
 				if !isString(v) { // Pre-check value type.
 					// All values must be of type string.
-					return parsedPolicy, probe.NewError(fmt.Errorf("Unknown type %s of conditional field value %s found in POST policy form.",
-						reflect.TypeOf(condt).String(), condt))
+					return parsedPolicy, fmt.Errorf("Unknown type %s of conditional field value %s found in POST policy form.", reflect.TypeOf(condt).String(), condt)
 				}
 				// {"acl": "public-read" } is an alternate way to indicate - [ "eq", "$acl", "public-read" ]
 				// In this case we will just collapse this into "eq" for all use cases.
@@ -117,16 +114,14 @@ func parsePostPolicyFormV4(policy string) (PostPolicyForm, *probe.Error) {
 			}
 		case []interface{}: // Handle array types.
 			if len(condt) != 3 { // Return error if we have insufficient elements.
-				return parsedPolicy, probe.NewError(fmt.Errorf("Malformed conditional fields %s of type %s found in POST policy form.",
-					condt, reflect.TypeOf(condt).String()))
+				return parsedPolicy, fmt.Errorf("Malformed conditional fields %s of type %s found in POST policy form.", condt, reflect.TypeOf(condt).String())
 			}
 			switch toString(condt[0]) {
 			case "eq", "starts-with":
 				for _, v := range condt { // Pre-check all values for type.
 					if !isString(v) {
 						// All values must be of type string.
-						return parsedPolicy, probe.NewError(fmt.Errorf("Unknown type %s of conditional field value %s found in POST policy form.",
-							reflect.TypeOf(condt).String(), condt))
+						return parsedPolicy, fmt.Errorf("Unknown type %s of conditional field value %s found in POST policy form.", reflect.TypeOf(condt).String(), condt)
 					}
 				}
 				operator, matchType, value := toString(condt[0]), toString(condt[1]), toString(condt[2])
@@ -147,12 +142,10 @@ func parsePostPolicyFormV4(policy string) (PostPolicyForm, *probe.Error) {
 				}
 			default:
 				// Condition should be valid.
-				return parsedPolicy, probe.NewError(fmt.Errorf("Unknown type %s of conditional field value %s found in POST policy form.",
-					reflect.TypeOf(condt).String(), condt))
+				return parsedPolicy, fmt.Errorf("Unknown type %s of conditional field value %s found in POST policy form.", reflect.TypeOf(condt).String(), condt)
 			}
 		default:
-			return parsedPolicy, probe.NewError(fmt.Errorf("Unknown field %s of type %s found in POST policy form.",
-				condt, reflect.TypeOf(condt).String()))
+			return parsedPolicy, fmt.Errorf("Unknown field %s of type %s found in POST policy form.", condt, reflect.TypeOf(condt).String())
 		}
 	}
 	return parsedPolicy, nil
diff --git a/update-main.go b/update-main.go
index 617c5c9b3..90cad8452 100644
--- a/update-main.go
+++ b/update-main.go
@@ -28,7 +28,6 @@ import (
 	"github.com/fatih/color"
 	"github.com/minio/cli"
 	"github.com/minio/mc/pkg/console"
-	"github.com/minio/minio/pkg/probe"
 )
 
 // command specific flags.
@@ -90,7 +89,7 @@ func (u updateMessage) String() string {
 		return updateMessage("You are already running the most recent version of ‘minio’.")
 	}
 	msg, err := colorizeUpdateMessage(u.Download)
-	fatalIf(err.Trace(msg), "Unable to colorize experimental update notification string ‘"+msg+"’.", nil)
+	fatalIf(err, "Unable to colorize experimental update notification string ‘"+msg+"’.", nil)
 	return msg
 }
 
@@ -98,38 +97,38 @@ func (u updateMessage) String() string {
 func (u updateMessage) JSON() string {
 	u.Status = "success"
 	updateMessageJSONBytes, err := json.Marshal(u)
-	fatalIf(probe.NewError(err), "Unable to marshal into JSON.", nil)
+	fatalIf((err), "Unable to marshal into JSON.", nil)
 
 	return string(updateMessageJSONBytes)
 }
 
-func parseReleaseData(data string) (time.Time, *probe.Error) {
+func parseReleaseData(data string) (time.Time, error) {
 	releaseStr := strings.Fields(data)
 	if len(releaseStr) < 2 {
-		return time.Time{}, probe.NewError(errors.New("Update data malformed"))
+		return time.Time{}, errors.New("Update data malformed")
 	}
 	releaseDate := releaseStr[1]
 	releaseDateSplits := strings.SplitN(releaseDate, ".", 3)
 	if len(releaseDateSplits) < 3 {
-		return time.Time{}, probe.NewError(errors.New("Update data malformed"))
+		return time.Time{}, (errors.New("Update data malformed"))
 	}
 	if releaseDateSplits[0] != "minio" {
-		return time.Time{}, probe.NewError(errors.New("Update data malformed, missing minio tag"))
+		return time.Time{}, (errors.New("Update data malformed, missing minio tag"))
 	}
 	// "OFFICIAL" tag is still kept for backward compatibility, we should remove this for the next release.
 	if releaseDateSplits[1] != "RELEASE" && releaseDateSplits[1] != "OFFICIAL" {
-		return time.Time{}, probe.NewError(errors.New("Update data malformed, missing RELEASE tag"))
+		return time.Time{}, (errors.New("Update data malformed, missing RELEASE tag"))
 	}
 	dateSplits := strings.SplitN(releaseDateSplits[2], "T", 2)
 	if len(dateSplits) < 2 {
-		return time.Time{}, probe.NewError(errors.New("Update data malformed, not in modified RFC3359 form"))
+		return time.Time{}, (errors.New("Update data malformed, not in modified RFC3359 form"))
 	}
 	dateSplits[1] = strings.Replace(dateSplits[1], "-", ":", -1)
 	date := strings.Join(dateSplits, "T")
 
-	parsedDate, e := time.Parse(time.RFC3339, date)
-	if e != nil {
-		return time.Time{}, probe.NewError(e)
+	parsedDate, err := time.Parse(time.RFC3339, date)
+	if err != nil {
+		return time.Time{}, err
 	}
 	return parsedDate, nil
 }
@@ -159,32 +158,32 @@ func getReleaseUpdate(updateURL string, noError bool) updateMessage {
 
 	// Instantiate a new client with 1 sec timeout.
 	client := &http.Client{
-		Timeout: 500 * time.Millisecond,
+		Timeout: 1 * time.Millisecond,
 	}
 
 	// Fetch new update.
-	data, e := client.Get(newUpdateURL)
-	if e != nil && noError {
+	data, err := client.Get(newUpdateURL)
+	if err != nil && noError {
 		return updateMsg
 	}
-	fatalIf(probe.NewError(e), "Unable to read from update URL ‘"+newUpdateURL+"’.", nil)
+	fatalIf((err), "Unable to read from update URL ‘"+newUpdateURL+"’.", nil)
 
 	// Error out if 'update' command is issued for development based builds.
 	if minioVersion == "DEVELOPMENT.GOGET" && !noError {
-		fatalIf(probe.NewError(errors.New("")),
+		fatalIf((errors.New("")),
 			"Update mechanism is not supported for ‘go get’ based binary builds. Please download official releases from https://minio.io/#minio", nil)
 	}
 
 	// Parse current minio version into RFC3339.
-	current, e := time.Parse(time.RFC3339, minioVersion)
-	if e != nil && noError {
+	current, err := time.Parse(time.RFC3339, minioVersion)
+	if err != nil && noError {
 		return updateMsg
 	}
-	fatalIf(probe.NewError(e), "Unable to parse version string as time.", nil)
+	fatalIf((err), "Unable to parse version string as time.", nil)
 
 	// Verify if current minio version is zero.
 	if current.IsZero() && !noError {
-		fatalIf(probe.NewError(errors.New("")),
+		fatalIf((errors.New("")),
 			"Updates not supported for custom builds. Version field is empty. Please download official releases from https://minio.io/#minio", nil)
 	}
 
@@ -195,27 +194,27 @@ func getReleaseUpdate(updateURL string, noError bool) updateMessage {
 			if noError {
 				return updateMsg
 			}
-			fatalIf(probe.NewError(errors.New("")), "Update server responsed with "+data.Status, nil)
+			fatalIf((errors.New("")), "Update server responsed with "+data.Status, nil)
 		}
 	}
 
 	// Read the response body.
-	updateBody, e := ioutil.ReadAll(data.Body)
-	if e != nil && noError {
+	updateBody, err := ioutil.ReadAll(data.Body)
+	if err != nil && noError {
 		return updateMsg
 	}
-	fatalIf(probe.NewError(e), "Fetching updates failed. Please try again.", nil)
+	fatalIf((err), "Fetching updates failed. Please try again.", nil)
 
 	// Parse the date if its valid.
 	latest, err := parseReleaseData(string(updateBody))
 	if err != nil && noError {
 		return updateMsg
 	}
-	fatalIf(err.Trace(updateURL), "Please report this issue at https://github.com/minio/minio/issues.", nil)
+	fatalIf(err, "Please report this issue at https://github.com/minio/minio/issues.", nil)
 
 	// Verify if the date is not zero.
 	if latest.IsZero() && !noError {
-		fatalIf(probe.NewError(errors.New("")),
+		fatalIf((errors.New("")),
 			"Unable to validate any update available at this time. Please open an issue at https://github.com/minio/minio/issues", nil)
 	}
 
diff --git a/utils.go b/utils.go
index d4de6fac5..aea79e3b6 100644
--- a/utils.go
+++ b/utils.go
@@ -19,7 +19,6 @@ package main
 import (
 	"encoding/base64"
 	"encoding/xml"
-	"github.com/minio/minio/pkg/probe"
 	"io"
 	"strings"
 )
@@ -31,12 +30,8 @@ func xmlDecoder(body io.Reader, v interface{}) error {
 }
 
 // checkValidMD5 - verify if valid md5, returns md5 in bytes.
-func checkValidMD5(md5 string) ([]byte, *probe.Error) {
-	md5Bytes, e := base64.StdEncoding.DecodeString(strings.TrimSpace(md5))
-	if e != nil {
-		return nil, probe.NewError(e)
-	}
-	return md5Bytes, nil
+func checkValidMD5(md5 string) ([]byte, error) {
+	return base64.StdEncoding.DecodeString(strings.TrimSpace(md5))
 }
 
 /// http://docs.aws.amazon.com/AmazonS3/latest/dev/UploadingObjects.html
@@ -56,6 +51,5 @@ func contains(stringList []string, element string) bool {
 			return true
 		}
 	}
-
 	return false
 }
diff --git a/web-handlers.go b/web-handlers.go
index 1b297961e..cf2fbe55c 100644
--- a/web-handlers.go
+++ b/web-handlers.go
@@ -109,9 +109,8 @@ func (web *webAPIHandlers) MakeBucket(r *http.Request, args *MakeBucketArgs, rep
 		return &json2.Error{Message: "Unauthorized request"}
 	}
 	reply.UIVersion = miniobrowser.UIVersion
-	e := web.ObjectAPI.MakeBucket(args.BucketName)
-	if e != nil {
-		return &json2.Error{Message: e.Cause.Error()}
+	if err := web.ObjectAPI.MakeBucket(args.BucketName); err != nil {
+		return &json2.Error{Message: err.Error()}
 	}
 	return nil
 }
@@ -139,9 +138,9 @@ func (web *webAPIHandlers) ListBuckets(r *http.Request, args *WebGenericArgs, re
 	if !isJWTReqAuthenticated(r) {
 		return &json2.Error{Message: "Unauthorized request"}
 	}
-	buckets, e := web.ObjectAPI.ListBuckets()
-	if e != nil {
-		return &json2.Error{Message: e.Cause.Error()}
+	buckets, err := web.ObjectAPI.ListBuckets()
+	if err != nil {
+		return &json2.Error{Message: err.Error()}
 	}
 	for _, bucket := range buckets {
 		// List all buckets which are not private.
@@ -191,7 +190,7 @@ func (web *webAPIHandlers) ListObjects(r *http.Request, args *ListObjectsArgs, r
 	for {
 		lo, err := web.ObjectAPI.ListObjects(args.BucketName, args.Prefix, marker, "/", 1000)
 		if err != nil {
-			return &json2.Error{Message: err.Cause.Error()}
+			return &json2.Error{Message: err.Error()}
 		}
 		marker = lo.NextMarker
 		for _, obj := range lo.Objects {
@@ -227,9 +226,8 @@ func (web *webAPIHandlers) RemoveObject(r *http.Request, args *RemoveObjectArgs,
 		return &json2.Error{Message: "Unauthorized request"}
 	}
 	reply.UIVersion = miniobrowser.UIVersion
-	e := web.ObjectAPI.DeleteObject(args.BucketName, args.ObjectName)
-	if e != nil {
-		return &json2.Error{Message: e.Cause.Error()}
+	if err := web.ObjectAPI.DeleteObject(args.BucketName, args.ObjectName); err != nil {
+		return &json2.Error{Message: err.Error()}
 	}
 	return nil
 }
@@ -252,7 +250,7 @@ func (web *webAPIHandlers) Login(r *http.Request, args *LoginArgs, reply *LoginR
 	if jwt.Authenticate(args.Username, args.Password) {
 		token, err := jwt.GenerateToken(args.Username)
 		if err != nil {
-			return &json2.Error{Message: err.Cause.Error(), Data: err.String()}
+			return &json2.Error{Message: err.Error()}
 		}
 		reply.Token = token
 		reply.UIVersion = miniobrowser.UIVersion
@@ -305,7 +303,7 @@ func (web *webAPIHandlers) SetAuth(r *http.Request, args *SetAuthArgs, reply *Se
 	cred := credential{args.AccessKey, args.SecretKey}
 	serverConfig.SetCredential(cred)
 	if err := serverConfig.Save(); err != nil {
-		return &json2.Error{Message: err.Cause.Error()}
+		return &json2.Error{Message: err.Error()}
 	}
 
 	jwt := initJWT()
@@ -314,7 +312,7 @@ func (web *webAPIHandlers) SetAuth(r *http.Request, args *SetAuthArgs, reply *Se
 	}
 	token, err := jwt.GenerateToken(args.AccessKey)
 	if err != nil {
-		return &json2.Error{Message: err.Cause.Error()}
+		return &json2.Error{Message: err.Error()}
 	}
 	reply.Token = token
 	reply.UIVersion = miniobrowser.UIVersion
@@ -350,7 +348,7 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
 	bucket := vars["bucket"]
 	object := vars["object"]
 	if _, err := web.ObjectAPI.PutObject(bucket, object, -1, r.Body, nil); err != nil {
-		writeWebErrorResponse(w, err.ToGoError())
+		writeWebErrorResponse(w, err)
 	}
 }
 
@@ -377,10 +375,10 @@ func (web *webAPIHandlers) Download(w http.ResponseWriter, r *http.Request) {
 
 	objReader, err := web.ObjectAPI.GetObject(bucket, object, 0)
 	if err != nil {
-		writeWebErrorResponse(w, err.ToGoError())
+		writeWebErrorResponse(w, err)
 		return
 	}
-	if _, e := io.Copy(w, objReader); e != nil {
+	if _, err := io.Copy(w, objReader); err != nil {
 		/// No need to print error, response writer already written to.
 		return
 	}
diff --git a/web-router.go b/web-router.go
index 00d16221d..6e063a43a 100644
--- a/web-router.go
+++ b/web-router.go
@@ -30,7 +30,7 @@ import (
 
 // webAPI container for Web API.
 type webAPIHandlers struct {
-	ObjectAPI objectAPI
+	ObjectAPI ObjectLayer
 }
 
 // indexHandler - Handler to serve index.html
diff --git a/xl-v1-common.go b/xl-erasure-v1-common.go
similarity index 100%
rename from xl-v1-common.go
rename to xl-erasure-v1-common.go
diff --git a/xl-v1-createfile.go b/xl-erasure-v1-createfile.go
similarity index 100%
rename from xl-v1-createfile.go
rename to xl-erasure-v1-createfile.go
diff --git a/xl-v1-errors.go b/xl-erasure-v1-errors.go
similarity index 100%
rename from xl-v1-errors.go
rename to xl-erasure-v1-errors.go
diff --git a/xl-v1-healfile.go b/xl-erasure-v1-healfile.go
similarity index 100%
rename from xl-v1-healfile.go
rename to xl-erasure-v1-healfile.go
diff --git a/xl-v1-metadata.go b/xl-erasure-v1-metadata.go
similarity index 100%
rename from xl-v1-metadata.go
rename to xl-erasure-v1-metadata.go
diff --git a/xl-v1-readfile.go b/xl-erasure-v1-readfile.go
similarity index 100%
rename from xl-v1-readfile.go
rename to xl-erasure-v1-readfile.go
diff --git a/xl-v1-utils.go b/xl-erasure-v1-utils.go
similarity index 100%
rename from xl-v1-utils.go
rename to xl-erasure-v1-utils.go
diff --git a/xl-v1-waitcloser.go b/xl-erasure-v1-waitcloser.go
similarity index 100%
rename from xl-v1-waitcloser.go
rename to xl-erasure-v1-waitcloser.go
diff --git a/xl-v1.go b/xl-erasure-v1.go
similarity index 98%
rename from xl-v1.go
rename to xl-erasure-v1.go
index c70ae3caf..82e82f3ee 100644
--- a/xl-v1.go
+++ b/xl-erasure-v1.go
@@ -83,7 +83,7 @@ func newXL(disks ...string) (StorageAPI, error) {
 	storageDisks := make([]StorageAPI, len(disks))
 	for index, disk := range disks {
 		var err error
-		storageDisks[index], err = newFS(disk)
+		storageDisks[index], err = newPosix(disk)
 		if err != nil {
 			return nil, err
 		}
@@ -573,6 +573,7 @@ func (xl XL) DeleteFile(volume, path string) error {
 
 // RenameFile - rename file.
 func (xl XL) RenameFile(srcVolume, srcPath, dstVolume, dstPath string) error {
+	// Validate inputs.
 	if !isValidVolname(srcVolume) {
 		return errInvalidArgument
 	}
@@ -587,6 +588,12 @@ func (xl XL) RenameFile(srcVolume, srcPath, dstVolume, dstPath string) error {
 	}
 	for _, disk := range xl.storageDisks {
 		if err := disk.RenameFile(srcVolume, srcPath, dstVolume, dstPath); err != nil {
+			log.WithFields(logrus.Fields{
+				"srcVolume": srcVolume,
+				"srcPath":   srcPath,
+				"dstVolume": dstVolume,
+				"dstPath":   dstPath,
+			}).Errorf("RenameFile failed with %s", err)
 			return err
 		}
 	}
diff --git a/xl-objects-multipart.go b/xl-objects-multipart.go
new file mode 100644
index 000000000..b69cb3516
--- /dev/null
+++ b/xl-objects-multipart.go
@@ -0,0 +1,531 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"path"
+	"strconv"
+	"strings"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/skyrings/skyring-common/tools/uuid"
+)
+
+// listLeafEntries - lists all entries if a given prefixPath is a leaf
+// directory, returns error if any - returns empty list if prefixPath
+// is not a leaf directory.
+func (xl xlObjects) listLeafEntries(prefixPath string) (entries []FileInfo, e error) {
+	var markerPath string
+	for {
+		fileInfos, eof, err := xl.storage.ListFiles(minioMetaVolume, prefixPath, markerPath, false, 1000)
+		if err != nil {
+			log.WithFields(logrus.Fields{
+				"prefixPath": prefixPath,
+				"markerPath": markerPath,
+			}).Errorf("%s", err)
+			return nil, err
+		}
+		for _, fileInfo := range fileInfos {
+			// Set marker for next batch of ListFiles.
+			markerPath = fileInfo.Name
+			if fileInfo.Mode.IsDir() {
+				// If a directory is found, doesn't return anything.
+				return nil, nil
+			}
+			fileName := path.Base(fileInfo.Name)
+			if !strings.Contains(fileName, ".") {
+				// Skip the entry if it is of the pattern bucket/object/uploadID.partNum.md5sum
+				// and retain entries of the pattern bucket/object/uploadID
+				entries = append(entries, fileInfo)
+			}
+		}
+		if eof {
+			break
+		}
+	}
+	return entries, nil
+}
+
+// listMetaVolumeFiles - list all files at a given prefix inside minioMetaVolume.
+func (xl xlObjects) listMetaVolumeFiles(prefixPath string, markerPath string, recursive bool, maxKeys int) (allFileInfos []FileInfo, eof bool, err error) {
+	// newMaxKeys tracks the size of entries which are going to be
+	// returned back.
+	var newMaxKeys int
+
+	// Following loop gathers and filters out special files inside
+	// minio meta volume.
+	for {
+		var fileInfos []FileInfo
+		// List files up to maxKeys-newMaxKeys, since we are skipping entries for special files.
+		fileInfos, eof, err = xl.storage.ListFiles(minioMetaVolume, prefixPath, markerPath, recursive, maxKeys-newMaxKeys)
+		if err != nil {
+			log.WithFields(logrus.Fields{
+				"prefixPath": prefixPath,
+				"markerPath": markerPath,
+				"recursive":  recursive,
+				"maxKeys":    maxKeys,
+			}).Errorf("%s", err)
+			return nil, true, err
+		}
+		// Loop through and validate individual file.
+		for _, fi := range fileInfos {
+			var entries []FileInfo
+			if fi.Mode.IsDir() {
+				// List all the entries if fi.Name is a leaf directory, if
+				// fi.Name is not a leaf directory then the resulting
+				// entries are empty.
+				entries, err = xl.listLeafEntries(fi.Name)
+				if err != nil {
+					log.WithFields(logrus.Fields{
+						"prefixPath": fi.Name,
+					}).Errorf("%s", err)
+					return nil, false, err
+				}
+			}
+			// Set markerPath for next batch of listing.
+			markerPath = fi.Name
+			if len(entries) > 0 {
+				// We reach here for non-recursive case and a leaf entry.
+				for _, entry := range entries {
+					allFileInfos = append(allFileInfos, entry)
+					newMaxKeys++
+					// If we have reached the maxKeys, it means we have listed
+					// everything that was requested. Return right here.
+					if newMaxKeys == maxKeys {
+						// Return values:
+						// allFileInfos : "maxKeys" number of entries.
+						// eof : eof returned by xl.storage.ListFiles()
+						// error : nil
+						return
+					}
+				}
+			} else {
+				// We reach here for a non-recursive case non-leaf entry
+				// OR recursive case with fi.Name matching pattern bucket/object/uploadID[.partNum.md5sum]
+				if !fi.Mode.IsDir() { // Do not skip non-recursive case directory entries.
+					// Skip files matching pattern bucket/object/uploadID.partNum.md5sum
+					// and retain files matching pattern bucket/object/uploadID
+					specialFile := path.Base(fi.Name)
+					if strings.Contains(specialFile, ".") {
+						// Contains partnumber and md5sum info, skip this.
+						continue
+					}
+				}
+			}
+			allFileInfos = append(allFileInfos, fi)
+			newMaxKeys++
+			// If we have reached the maxKeys, it means we have listed
+			// everything that was requested. Return right here.
+			if newMaxKeys == maxKeys {
+				// Return values:
+				// allFileInfos : "maxKeys" number of entries.
+				// eof : eof returned by xl.storage.ListFiles()
+				// error : nil
+				return
+			}
+		}
+		// If we have reached eof then we break out.
+		if eof {
+			break
+		}
+	}
+
+	// Return entries here.
+	return allFileInfos, eof, nil
+}
+
+// ListMultipartUploads - list multipart uploads.
+func (xl xlObjects) ListMultipartUploads(bucket, prefix, keyMarker, uploadIDMarker, delimiter string, maxUploads int) (ListMultipartsInfo, error) {
+	result := ListMultipartsInfo{}
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return ListMultipartsInfo{}, (BucketNameInvalid{Bucket: bucket})
+	}
+	if !IsValidObjectPrefix(prefix) {
+		return ListMultipartsInfo{}, (ObjectNameInvalid{Bucket: bucket, Object: prefix})
+	}
+	// Verify if delimiter is anything other than '/', which we do not support.
+	if delimiter != "" && delimiter != slashSeparator {
+		return ListMultipartsInfo{}, (UnsupportedDelimiter{
+			Delimiter: delimiter,
+		})
+	}
+	// Verify if marker has prefix.
+	if keyMarker != "" && !strings.HasPrefix(keyMarker, prefix) {
+		return ListMultipartsInfo{}, (InvalidMarkerPrefixCombination{
+			Marker: keyMarker,
+			Prefix: prefix,
+		})
+	}
+	if uploadIDMarker != "" {
+		if strings.HasSuffix(keyMarker, slashSeparator) {
+			return result, (InvalidUploadIDKeyCombination{
+				UploadIDMarker: uploadIDMarker,
+				KeyMarker:      keyMarker,
+			})
+		}
+		id, err := uuid.Parse(uploadIDMarker)
+		if err != nil {
+			return result, err
+		}
+		if id.IsZero() {
+			return result, (MalformedUploadID{
+				UploadID: uploadIDMarker,
+			})
+		}
+	}
+
+	recursive := true
+	if delimiter == slashSeparator {
+		recursive = false
+	}
+
+	result.IsTruncated = true
+	result.MaxUploads = maxUploads
+
+	// Not using path.Join() as it strips off the trailing '/'.
+	// Also bucket should always be followed by '/' even if prefix is empty.
+	prefixPath := pathJoin(bucket, prefix)
+	keyMarkerPath := ""
+	if keyMarker != "" {
+		keyMarkerPath = pathJoin(pathJoin(bucket, keyMarker), uploadIDMarker)
+	}
+	// List all the multipart files at prefixPath, starting with marker keyMarkerPath.
+	fileInfos, eof, err := xl.listMetaVolumeFiles(prefixPath, keyMarkerPath, recursive, maxUploads)
+	if err != nil {
+		log.WithFields(logrus.Fields{
+			"prefixPath": prefixPath,
+			"markerPath": keyMarkerPath,
+			"recursive":  recursive,
+			"maxUploads": maxUploads,
+		}).Errorf("listMetaVolumeFiles failed with %s", err)
+		return ListMultipartsInfo{}, err
+	}
+
+	// Loop through all the received files fill in the multiparts result.
+	for _, fi := range fileInfos {
+		var objectName string
+		var uploadID string
+		if fi.Mode.IsDir() {
+			// All directory entries are common prefixes.
+			uploadID = "" // Upload ids are empty for CommonPrefixes.
+			objectName = strings.TrimPrefix(fi.Name, retainSlash(bucket))
+			result.CommonPrefixes = append(result.CommonPrefixes, objectName)
+		} else {
+			uploadID = path.Base(fi.Name)
+			objectName = strings.TrimPrefix(path.Dir(fi.Name), retainSlash(bucket))
+			result.Uploads = append(result.Uploads, uploadMetadata{
+				Object:    objectName,
+				UploadID:  uploadID,
+				Initiated: fi.ModTime,
+			})
+		}
+		result.NextKeyMarker = objectName
+		result.NextUploadIDMarker = uploadID
+	}
+	result.IsTruncated = !eof
+	if !result.IsTruncated {
+		result.NextKeyMarker = ""
+		result.NextUploadIDMarker = ""
+	}
+	return result, nil
+}
+
+func (xl xlObjects) NewMultipartUpload(bucket, object string) (string, error) {
+	// Verify if bucket name is valid.
+	if !IsValidBucketName(bucket) {
+		return "", (BucketNameInvalid{Bucket: bucket})
+	}
+	// Verify if object name is valid.
+	if !IsValidObjectName(object) {
+		return "", ObjectNameInvalid{Bucket: bucket, Object: object}
+	}
+	// Verify whether the bucket exists.
+	if isExist, err := xl.isBucketExist(bucket); err != nil {
+		return "", err
+	} else if !isExist {
+		return "", BucketNotFound{Bucket: bucket}
+	}
+
+	if _, err := xl.storage.StatVol(minioMetaVolume); err != nil {
+		if err == errVolumeNotFound {
+			err = xl.storage.MakeVol(minioMetaVolume)
+			if err != nil {
+				return "", toObjectErr(err)
+			}
+		}
+	}
+	for {
+		uuid, err := uuid.New()
+		if err != nil {
+			return "", err
+		}
+		uploadID := uuid.String()
+		uploadIDPath := path.Join(bucket, object, uploadID)
+		if _, err = xl.storage.StatFile(minioMetaVolume, uploadIDPath); err != nil {
+			if err != errFileNotFound {
+				return "", (toObjectErr(err, minioMetaVolume, uploadIDPath))
+			}
+			// uploadIDPath doesn't exist, so create empty file to reserve the name
+			var w io.WriteCloser
+			if w, err = xl.storage.CreateFile(minioMetaVolume, uploadIDPath); err == nil {
+				// Close the writer.
+				if err = w.Close(); err != nil {
+					return "", err
+				}
+			} else {
+				return "", toObjectErr(err, minioMetaVolume, uploadIDPath)
+			}
+			return uploadID, nil
+		}
+		// uploadIDPath already exists.
+		// loop again to try with different uuid generated.
+	}
+}
+
+// isUploadIDExists - verify if a given uploadID exists and is valid.
+func (xl xlObjects) isUploadIDExists(bucket, object, uploadID string) (bool, error) {
+	uploadIDPath := path.Join(bucket, object, uploadID)
+	st, err := xl.storage.StatFile(minioMetaVolume, uploadIDPath)
+	if err != nil {
+		// Upload id does not exist.
+		if err == errFileNotFound {
+			return false, nil
+		}
+		return false, err
+	}
+	// Upload id exists and is a regular file.
+	return st.Mode.IsRegular(), nil
+}
+
+// PutObjectPart - writes the multipart upload chunks.
+func (xl xlObjects) PutObjectPart(bucket, object, uploadID string, partID int, size int64, data io.Reader, md5Hex string) (string, error) {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return "", BucketNameInvalid{Bucket: bucket}
+	}
+	if !IsValidObjectName(object) {
+		return "", ObjectNameInvalid{Bucket: bucket, Object: object}
+	}
+	// Verify whether the bucket exists.
+	if isExist, err := xl.isBucketExist(bucket); err != nil {
+		return "", err
+	} else if !isExist {
+		return "", BucketNotFound{Bucket: bucket}
+	}
+
+	if status, err := xl.isUploadIDExists(bucket, object, uploadID); err != nil {
+		return "", err
+	} else if !status {
+		return "", InvalidUploadID{UploadID: uploadID}
+	}
+
+	partSuffix := fmt.Sprintf("%s.%d.%s", uploadID, partID, md5Hex)
+	fileWriter, err := xl.storage.CreateFile(minioMetaVolume, path.Join(bucket, object, partSuffix))
+	if err != nil {
+		return "", toObjectErr(err, bucket, object)
+	}
+
+	// Initialize md5 writer.
+	md5Writer := md5.New()
+
+	// Instantiate a new multi writer.
+	multiWriter := io.MultiWriter(md5Writer, fileWriter)
+
+	// Instantiate checksum hashers and create a multiwriter.
+	if size > 0 {
+		if _, err = io.CopyN(multiWriter, data, size); err != nil {
+			safeCloseAndRemove(fileWriter)
+			return "", (toObjectErr(err))
+		}
+		// Reader shouldn't have more data what mentioned in size argument.
+		// reading one more byte from the reader to validate it.
+		// expected to fail, success validates existence of more data in the reader.
+		if _, err = io.CopyN(ioutil.Discard, data, 1); err == nil {
+			safeCloseAndRemove(fileWriter)
+			return "", (UnExpectedDataSize{Size: int(size)})
+		}
+	} else {
+		if _, err = io.Copy(multiWriter, data); err != nil {
+			safeCloseAndRemove(fileWriter)
+			return "", (toObjectErr(err))
+		}
+	}
+
+	newMD5Hex := hex.EncodeToString(md5Writer.Sum(nil))
+	if md5Hex != "" {
+		if newMD5Hex != md5Hex {
+			safeCloseAndRemove(fileWriter)
+			return "", (BadDigest{md5Hex, newMD5Hex})
+		}
+	}
+	err = fileWriter.Close()
+	if err != nil {
+		return "", err
+	}
+	return newMD5Hex, nil
+}
+
+func (xl xlObjects) ListObjectParts(bucket, object, uploadID string, partNumberMarker, maxParts int) (ListPartsInfo, error) {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return ListPartsInfo{}, (BucketNameInvalid{Bucket: bucket})
+	}
+	if !IsValidObjectName(object) {
+		return ListPartsInfo{}, (ObjectNameInvalid{Bucket: bucket, Object: object})
+	}
+	if status, err := xl.isUploadIDExists(bucket, object, uploadID); err != nil {
+		return ListPartsInfo{}, err
+	} else if !status {
+		return ListPartsInfo{}, (InvalidUploadID{UploadID: uploadID})
+	}
+	result := ListPartsInfo{}
+	var markerPath string
+	nextPartNumberMarker := 0
+	uploadIDPath := path.Join(bucket, object, uploadID)
+	// Figure out the marker for the next subsequent calls, if the
+	// partNumberMarker is already set.
+	if partNumberMarker > 0 {
+		partNumberMarkerPath := uploadIDPath + "." + strconv.Itoa(partNumberMarker) + "."
+		fileInfos, _, err := xl.storage.ListFiles(minioMetaVolume, partNumberMarkerPath, "", false, 1)
+		if err != nil {
+			return result, toObjectErr(err, minioMetaVolume, partNumberMarkerPath)
+		}
+		if len(fileInfos) == 0 {
+			return result, (InvalidPart{})
+		}
+		markerPath = fileInfos[0].Name
+	}
+	uploadIDPrefix := uploadIDPath + "."
+	fileInfos, eof, err := xl.storage.ListFiles(minioMetaVolume, uploadIDPrefix, markerPath, false, maxParts)
+	if err != nil {
+		return result, InvalidPart{}
+	}
+	for _, fileInfo := range fileInfos {
+		fileName := path.Base(fileInfo.Name)
+		splitResult := strings.Split(fileName, ".")
+		partNum, err := strconv.Atoi(splitResult[1])
+		if err != nil {
+			return result, err
+		}
+		md5sum := splitResult[2]
+		result.Parts = append(result.Parts, partInfo{
+			PartNumber:   partNum,
+			LastModified: fileInfo.ModTime,
+			ETag:         md5sum,
+			Size:         fileInfo.Size,
+		})
+		nextPartNumberMarker = partNum
+	}
+	result.Bucket = bucket
+	result.Object = object
+	result.UploadID = uploadID
+	result.PartNumberMarker = partNumberMarker
+	result.NextPartNumberMarker = nextPartNumberMarker
+	result.MaxParts = maxParts
+	result.IsTruncated = !eof
+	return result, nil
+}
+
+func (xl xlObjects) CompleteMultipartUpload(bucket string, object string, uploadID string, parts []completePart) (string, error) {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return "", (BucketNameInvalid{Bucket: bucket})
+	}
+	if !IsValidObjectName(object) {
+		return "", (ObjectNameInvalid{
+			Bucket: bucket,
+			Object: object,
+		})
+	}
+	if status, err := xl.isUploadIDExists(bucket, object, uploadID); err != nil {
+		return "", err
+	} else if !status {
+		return "", (InvalidUploadID{UploadID: uploadID})
+	}
+
+	fileWriter, err := xl.storage.CreateFile(bucket, object)
+	if err != nil {
+		return "", toObjectErr(err, bucket, object)
+	}
+
+	var md5Sums []string
+	for _, part := range parts {
+		// Construct part suffix.
+		partSuffix := fmt.Sprintf("%s.%d.%s", uploadID, part.PartNumber, part.ETag)
+		err = xl.storage.RenameFile(minioMetaVolume, path.Join(bucket, object, partSuffix), bucket, path.Join(object, fmt.Sprint(part.PartNumber)))
+		if err != nil {
+			return "", err
+		}
+		md5Sums = append(md5Sums, part.ETag)
+	}
+
+	err = fileWriter.Close()
+	if err != nil {
+		return "", err
+	}
+
+	// Save the s3 md5.
+	s3MD5, err := makeS3MD5(md5Sums...)
+	if err != nil {
+		return "", err
+	}
+
+	// Return md5sum.
+	return s3MD5, nil
+}
+
+// AbortMultipartUpload - abort multipart upload.
+func (xl xlObjects) AbortMultipartUpload(bucket, object, uploadID string) error {
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return (BucketNameInvalid{Bucket: bucket})
+	}
+	if !IsValidObjectName(object) {
+		return (ObjectNameInvalid{Bucket: bucket, Object: object})
+	}
+	if status, err := xl.isUploadIDExists(bucket, object, uploadID); err != nil {
+		return err
+	} else if !status {
+		return (InvalidUploadID{UploadID: uploadID})
+	}
+
+	markerPath := ""
+	for {
+		uploadIDPath := path.Join(bucket, object, uploadID)
+		fileInfos, eof, err := xl.storage.ListFiles(minioMetaVolume, uploadIDPath, markerPath, false, 1000)
+		if err != nil {
+			if err == errFileNotFound {
+				return (InvalidUploadID{UploadID: uploadID})
+			}
+			return toObjectErr(err)
+		}
+		for _, fileInfo := range fileInfos {
+			xl.storage.DeleteFile(minioMetaVolume, fileInfo.Name)
+			markerPath = fileInfo.Name
+		}
+		if eof {
+			break
+		}
+	}
+	return nil
+}
diff --git a/object-api.go b/xl-objects.go
similarity index 53%
rename from object-api.go
rename to xl-objects.go
index 2027207d8..5f88707d9 100644
--- a/object-api.go
+++ b/xl-objects.go
@@ -27,26 +27,30 @@ import (
 	"strings"
 
 	"github.com/minio/minio/pkg/mimedb"
-	"github.com/minio/minio/pkg/probe"
-	"github.com/minio/minio/pkg/safe"
 )
 
 const (
 	multipartMetaFile = "multipart.json"
 )
 
-type objectAPI struct {
+// xlObjects - Implements fs object layer.
+type xlObjects struct {
 	storage StorageAPI
 }
 
-func newObjectLayer(storage StorageAPI) objectAPI {
-	return objectAPI{storage}
+// newXLObjects - initialize new xl object layer.
+func newXLObjects(exportPaths ...string) (ObjectLayer, error) {
+	storage, err := newXL(exportPaths...)
+	if err != nil {
+		return nil, err
+	}
+	return xlObjects{storage}, nil
 }
 
 // checks whether bucket exists.
-func (o objectAPI) isBucketExist(bucketName string) (bool, error) {
+func (xl xlObjects) isBucketExist(bucketName string) (bool, error) {
 	// Check whether bucket exists.
-	if _, e := o.storage.StatVol(bucketName); e != nil {
+	if _, e := xl.storage.StatVol(bucketName); e != nil {
 		if e == errVolumeNotFound {
 			return false, nil
 		}
@@ -58,35 +62,35 @@ func (o objectAPI) isBucketExist(bucketName string) (bool, error) {
 /// Bucket operations
 
 // MakeBucket - make a bucket.
-func (o objectAPI) MakeBucket(bucket string) *probe.Error {
+func (xl xlObjects) MakeBucket(bucket string) error {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return BucketNameInvalid{Bucket: bucket}
 	}
-	if e := o.storage.MakeVol(bucket); e != nil {
-		return probe.NewError(toObjectErr(e, bucket))
+	if err := xl.storage.MakeVol(bucket); err != nil {
+		return toObjectErr(err, bucket)
 	}
 	// This happens for the first time, but keep this here since this
 	// is the only place where it can be made expensive optimizing all
 	// other calls.
 	// Create minio meta volume, if it doesn't exist yet.
-	if e := o.storage.MakeVol(minioMetaVolume); e != nil {
-		if e != errVolumeExists {
-			return probe.NewError(toObjectErr(e, minioMetaVolume))
+	if err := xl.storage.MakeVol(minioMetaVolume); err != nil {
+		if err != errVolumeExists {
+			return toObjectErr(err, minioMetaVolume)
 		}
 	}
 	return nil
 }
 
 // GetBucketInfo - get bucket info.
-func (o objectAPI) GetBucketInfo(bucket string) (BucketInfo, *probe.Error) {
+func (xl xlObjects) GetBucketInfo(bucket string) (BucketInfo, error) {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return BucketInfo{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return BucketInfo{}, BucketNameInvalid{Bucket: bucket}
 	}
-	vi, e := o.storage.StatVol(bucket)
-	if e != nil {
-		return BucketInfo{}, probe.NewError(toObjectErr(e, bucket))
+	vi, err := xl.storage.StatVol(bucket)
+	if err != nil {
+		return BucketInfo{}, toObjectErr(err, bucket)
 	}
 	return BucketInfo{
 		Name:    bucket,
@@ -96,19 +100,12 @@ func (o objectAPI) GetBucketInfo(bucket string) (BucketInfo, *probe.Error) {
 	}, nil
 }
 
-// byBucketName is a collection satisfying sort.Interface.
-type byBucketName []BucketInfo
-
-func (d byBucketName) Len() int           { return len(d) }
-func (d byBucketName) Swap(i, j int)      { d[i], d[j] = d[j], d[i] }
-func (d byBucketName) Less(i, j int) bool { return d[i].Name < d[j].Name }
-
 // ListBuckets - list buckets.
-func (o objectAPI) ListBuckets() ([]BucketInfo, *probe.Error) {
+func (xl xlObjects) ListBuckets() ([]BucketInfo, error) {
 	var bucketInfos []BucketInfo
-	vols, e := o.storage.ListVols()
-	if e != nil {
-		return nil, probe.NewError(toObjectErr(e))
+	vols, err := xl.storage.ListVols()
+	if err != nil {
+		return nil, toObjectErr(err)
 	}
 	for _, vol := range vols {
 		// StorageAPI can send volume names which are incompatible
@@ -128,13 +125,13 @@ func (o objectAPI) ListBuckets() ([]BucketInfo, *probe.Error) {
 }
 
 // DeleteBucket - delete a bucket.
-func (o objectAPI) DeleteBucket(bucket string) *probe.Error {
+func (xl xlObjects) DeleteBucket(bucket string) error {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return BucketNameInvalid{Bucket: bucket}
 	}
-	if e := o.storage.DeleteVol(bucket); e != nil {
-		return probe.NewError(toObjectErr(e))
+	if err := xl.storage.DeleteVol(bucket); err != nil {
+		return toObjectErr(err)
 	}
 	return nil
 }
@@ -142,12 +139,12 @@ func (o objectAPI) DeleteBucket(bucket string) *probe.Error {
 /// Object Operations
 
 // GetObject - get an object.
-func (o objectAPI) GetObject(bucket, object string, startOffset int64) (io.ReadCloser, *probe.Error) {
+func (xl xlObjects) GetObject(bucket, object string, startOffset int64) (io.ReadCloser, error) {
 	findPathOffset := func() (i int, partOffset int64, err error) {
 		partOffset = startOffset
 		for i = 1; i < 10000; i++ {
 			var fileInfo FileInfo
-			fileInfo, err = o.storage.StatFile(bucket, pathJoin(object, fmt.Sprint(i)))
+			fileInfo, err = xl.storage.StatFile(bucket, pathJoin(object, fmt.Sprint(i)))
 			if err != nil {
 				if err == errFileNotFound {
 					continue
@@ -167,36 +164,31 @@ func (o objectAPI) GetObject(bucket, object string, startOffset int64) (io.ReadC
 
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return nil, probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return nil, BucketNameInvalid{Bucket: bucket}
 	}
 	// Verify if object is valid.
 	if !IsValidObjectName(object) {
-		return nil, probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
+		return nil, ObjectNameInvalid{Bucket: bucket, Object: object}
 	}
-	_, err := o.storage.StatFile(bucket, object)
-	if err == nil {
-		fmt.Println("1", err)
-		r, e := o.storage.ReadFile(bucket, object, startOffset)
-		if e != nil {
-			fmt.Println("1.5", err)
-			return nil, probe.NewError(toObjectErr(e, bucket, object))
+	if _, err := xl.storage.StatFile(bucket, pathJoin(object, multipartMetaFile)); err != nil {
+		if _, err = xl.storage.StatFile(bucket, object); err == nil {
+			var reader io.ReadCloser
+			reader, err = xl.storage.ReadFile(bucket, object, startOffset)
+			if err != nil {
+				return nil, toObjectErr(err, bucket, object)
+			}
+			return reader, nil
 		}
-		return r, nil
-	}
-	_, err = o.storage.StatFile(bucket, pathJoin(object, multipartMetaFile))
-	if err != nil {
-		fmt.Println("2", err)
-		return nil, probe.NewError(toObjectErr(err, bucket, object))
+		return nil, toObjectErr(err, bucket, object)
 	}
 	fileReader, fileWriter := io.Pipe()
 	partNum, offset, err := findPathOffset()
 	if err != nil {
-		fmt.Println("3", err)
-		return nil, probe.NewError(toObjectErr(err, bucket, object))
+		return nil, toObjectErr(err, bucket, object)
 	}
 	go func() {
 		for ; partNum < 10000; partNum++ {
-			r, err := o.storage.ReadFile(bucket, pathJoin(object, fmt.Sprint(partNum)), offset)
+			r, err := xl.storage.ReadFile(bucket, pathJoin(object, fmt.Sprint(partNum)), offset)
 			if err != nil {
 				if err == errFileNotFound {
 					continue
@@ -215,10 +207,10 @@ func (o objectAPI) GetObject(bucket, object string, startOffset int64) (io.ReadC
 }
 
 // GetObjectInfo - get object info.
-func (o objectAPI) GetObjectInfo(bucket, object string) (ObjectInfo, *probe.Error) {
+func (xl xlObjects) GetObjectInfo(bucket, object string) (ObjectInfo, error) {
 	getMultpartFileSize := func() (size int64) {
 		for i := 0; i < 10000; i++ {
-			fi, err := o.storage.StatFile(bucket, pathJoin(object, fmt.Sprint(i)))
+			fi, err := xl.storage.StatFile(bucket, pathJoin(object, fmt.Sprint(i)))
 			if err != nil {
 				continue
 			}
@@ -228,17 +220,17 @@ func (o objectAPI) GetObjectInfo(bucket, object string) (ObjectInfo, *probe.Erro
 	}
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return ObjectInfo{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return ObjectInfo{}, BucketNameInvalid{Bucket: bucket}
 	}
 	// Verify if object is valid.
 	if !IsValidObjectName(object) {
-		return ObjectInfo{}, probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
+		return ObjectInfo{}, ObjectNameInvalid{Bucket: bucket, Object: object}
 	}
-	fi, e := o.storage.StatFile(bucket, object)
-	if e != nil {
-		fi, e = o.storage.StatFile(bucket, pathJoin(object, multipartMetaFile))
-		if e != nil {
-			return ObjectInfo{}, probe.NewError(toObjectErr(e, bucket, object))
+	fi, err := xl.storage.StatFile(bucket, object)
+	if err != nil {
+		fi, err = xl.storage.StatFile(bucket, pathJoin(object, multipartMetaFile))
+		if err != nil {
+			return ObjectInfo{}, toObjectErr(err, bucket, object)
 		}
 		fi.Size = getMultpartFileSize()
 	}
@@ -260,44 +252,29 @@ func (o objectAPI) GetObjectInfo(bucket, object string) (ObjectInfo, *probe.Erro
 	}, nil
 }
 
-// safeCloseAndRemove - safely closes and removes underlying temporary
-// file writer if possible.
-func safeCloseAndRemove(writer io.WriteCloser) error {
-	// If writer is a safe file, Attempt to close and remove.
-	safeWriter, ok := writer.(*safe.File)
-	if ok {
-		return safeWriter.CloseAndRemove()
-	}
-	pipeWriter, ok := writer.(*io.PipeWriter)
-	if ok {
-		return pipeWriter.CloseWithError(errors.New("Close and error out."))
-	}
-	return nil
-}
-
-func (o objectAPI) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string) (string, *probe.Error) {
+func (xl xlObjects) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string) (string, error) {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return "", probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return "", (BucketNameInvalid{Bucket: bucket})
 	}
 	if !IsValidObjectName(object) {
-		return "", probe.NewError(ObjectNameInvalid{
+		return "", (ObjectNameInvalid{
 			Bucket: bucket,
 			Object: object,
 		})
 	}
 	// Check whether the bucket exists.
-	isExist, err := o.isBucketExist(bucket)
+	isExist, err := xl.isBucketExist(bucket)
 	if err != nil {
-		return "", probe.NewError(err)
+		return "", err
 	}
 	if !isExist {
-		return "", probe.NewError(BucketNotFound{Bucket: bucket})
+		return "", BucketNotFound{Bucket: bucket}
 	}
 
-	fileWriter, e := o.storage.CreateFile(bucket, object)
-	if e != nil {
-		return "", probe.NewError(toObjectErr(e, bucket, object))
+	fileWriter, err := xl.storage.CreateFile(bucket, object)
+	if err != nil {
+		return "", toObjectErr(err, bucket, object)
 	}
 
 	// Initialize md5 writer.
@@ -308,18 +285,18 @@ func (o objectAPI) PutObject(bucket string, object string, size int64, data io.R
 
 	// Instantiate checksum hashers and create a multiwriter.
 	if size > 0 {
-		if _, e = io.CopyN(multiWriter, data, size); e != nil {
+		if _, err = io.CopyN(multiWriter, data, size); err != nil {
 			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
-				return "", probe.NewError(clErr)
+				return "", clErr
 			}
-			return "", probe.NewError(toObjectErr(e))
+			return "", toObjectErr(err)
 		}
 	} else {
-		if _, e = io.Copy(multiWriter, data); e != nil {
+		if _, err = io.Copy(multiWriter, data); err != nil {
 			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
-				return "", probe.NewError(clErr)
+				return "", clErr
 			}
-			return "", probe.NewError(e)
+			return "", err
 		}
 	}
 
@@ -331,56 +308,56 @@ func (o objectAPI) PutObject(bucket string, object string, size int64, data io.R
 	}
 	if md5Hex != "" {
 		if newMD5Hex != md5Hex {
-			if e = safeCloseAndRemove(fileWriter); e != nil {
-				return "", probe.NewError(e)
+			if err = safeCloseAndRemove(fileWriter); err != nil {
+				return "", err
 			}
-			return "", probe.NewError(BadDigest{md5Hex, newMD5Hex})
+			return "", BadDigest{md5Hex, newMD5Hex}
 		}
 	}
-	e = fileWriter.Close()
-	if e != nil {
-		return "", probe.NewError(e)
+	err = fileWriter.Close()
+	if err != nil {
+		return "", err
 	}
 
 	// Return md5sum, successfully wrote object.
 	return newMD5Hex, nil
 }
 
-func (o objectAPI) DeleteObject(bucket, object string) *probe.Error {
+func (xl xlObjects) DeleteObject(bucket, object string) error {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return BucketNameInvalid{Bucket: bucket}
 	}
 	if !IsValidObjectName(object) {
-		return probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
+		return ObjectNameInvalid{Bucket: bucket, Object: object}
 	}
-	if e := o.storage.DeleteFile(bucket, object); e != nil {
-		return probe.NewError(toObjectErr(e, bucket, object))
+	if err := xl.storage.DeleteFile(bucket, object); err != nil {
+		return toObjectErr(err, bucket, object)
 	}
 	return nil
 }
 
-func (o objectAPI) ListObjects(bucket, prefix, marker, delimiter string, maxKeys int) (ListObjectsInfo, *probe.Error) {
+func (xl xlObjects) ListObjects(bucket, prefix, marker, delimiter string, maxKeys int) (ListObjectsInfo, error) {
 	// Verify if bucket is valid.
 	if !IsValidBucketName(bucket) {
-		return ListObjectsInfo{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
+		return ListObjectsInfo{}, BucketNameInvalid{Bucket: bucket}
 	}
 	if !IsValidObjectPrefix(prefix) {
-		return ListObjectsInfo{}, probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: prefix})
+		return ListObjectsInfo{}, ObjectNameInvalid{Bucket: bucket, Object: prefix}
 	}
 	// Verify if delimiter is anything other than '/', which we do not support.
 	if delimiter != "" && delimiter != slashSeparator {
-		return ListObjectsInfo{}, probe.NewError(UnsupportedDelimiter{
+		return ListObjectsInfo{}, UnsupportedDelimiter{
 			Delimiter: delimiter,
-		})
+		}
 	}
 	// Verify if marker has prefix.
 	if marker != "" {
 		if !strings.HasPrefix(marker, prefix) {
-			return ListObjectsInfo{}, probe.NewError(InvalidMarkerPrefixCombination{
+			return ListObjectsInfo{}, InvalidMarkerPrefixCombination{
 				Marker: marker,
 				Prefix: prefix,
-			})
+			}
 		}
 	}
 
@@ -389,9 +366,9 @@ func (o objectAPI) ListObjects(bucket, prefix, marker, delimiter string, maxKeys
 	if delimiter == slashSeparator {
 		recursive = false
 	}
-	fileInfos, eof, e := o.storage.ListFiles(bucket, prefix, marker, recursive, maxKeys)
-	if e != nil {
-		return ListObjectsInfo{}, probe.NewError(toObjectErr(e, bucket))
+	fileInfos, eof, err := xl.storage.ListFiles(bucket, prefix, marker, recursive, maxKeys)
+	if err != nil {
+		return ListObjectsInfo{}, toObjectErr(err, bucket)
 	}
 	if maxKeys == 0 {
 		return ListObjectsInfo{}, nil