diff --git a/pkg/storage/donut/donut.go b/pkg/storage/donut/donut.go
index 9e6aca2c4..23a0231fb 100644
--- a/pkg/storage/donut/donut.go
+++ b/pkg/storage/donut/donut.go
@@ -21,7 +21,7 @@ import "github.com/minio/minio/pkg/iodine"
 // donut struct internal data
 type donut struct {
 	name    string
-	buckets map[string]Bucket
+	buckets map[string]bucket
 	nodes   map[string]Node
 }
 
@@ -72,7 +72,7 @@ func NewDonut(donutName string, nodeDiskMap map[string][]string) (Donut, error)
 		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	nodes := make(map[string]Node)
-	buckets := make(map[string]Bucket)
+	buckets := make(map[string]bucket)
 	d := donut{
 		name:    donutName,
 		nodes:   nodes,
diff --git a/pkg/storage/donut/donut_bucket.go b/pkg/storage/donut/donut_bucket.go
index ef90146bc..e94ff6de4 100644
--- a/pkg/storage/donut/donut_bucket.go
+++ b/pkg/storage/donut/donut_bucket.go
@@ -38,18 +38,18 @@ type bucket struct {
 	time      time.Time
 	donutName string
 	nodes     map[string]Node
-	objects   map[string]Object
+	objects   map[string]object
 }
 
 // NewBucket - instantiate a new bucket
-func NewBucket(bucketName, aclType, donutName string, nodes map[string]Node) (Bucket, map[string]string, error) {
+func NewBucket(bucketName, aclType, donutName string, nodes map[string]Node) (bucket, map[string]string, error) {
 	errParams := map[string]string{
 		"bucketName": bucketName,
 		"donutName":  donutName,
 		"aclType":    aclType,
 	}
 	if strings.TrimSpace(bucketName) == "" || strings.TrimSpace(donutName) == "" {
-		return nil, nil, iodine.New(InvalidArgument{}, errParams)
+		return bucket{}, nil, iodine.New(InvalidArgument{}, errParams)
 	}
 	bucketMetadata := make(map[string]string)
 	bucketMetadata["acl"] = aclType
@@ -60,13 +60,13 @@ func NewBucket(bucketName, aclType, donutName string, nodes map[string]Node) (Bu
 	b.acl = aclType
 	b.time = t
 	b.donutName = donutName
-	b.objects = make(map[string]Object)
+	b.objects = make(map[string]object)
 	b.nodes = nodes
 	return b, bucketMetadata, nil
 }
 
 // ListObjects - list all objects
-func (b bucket) ListObjects() (map[string]Object, error) {
+func (b bucket) ListObjects() (map[string]object, error) {
 	nodeSlice := 0
 	for _, node := range b.nodes {
 		disks, err := node.ListDisks()
diff --git a/pkg/storage/donut/donut_bucket_internal.go b/pkg/storage/donut/donut_bucket_internal.go
index 39a35a016..deb6b898e 100644
--- a/pkg/storage/donut/donut_bucket_internal.go
+++ b/pkg/storage/donut/donut_bucket_internal.go
@@ -32,7 +32,7 @@ import (
 	"github.com/minio/minio/pkg/utils/split"
 )
 
-/// This file contains all the internal functions used by Bucket interface
+/// This file contains all the internal functions
 
 // isMD5SumEqual - returns error if md5sum mismatches, other its `nil`
 func (b bucket) isMD5SumEqual(expectedMD5Sum, actualMD5Sum string) error {
@@ -211,7 +211,7 @@ func (b bucket) readEncodedData(objectName string, writer *io.PipeWriter, donutO
 }
 
 // decodeEncodedData -
-func (b bucket) decodeEncodedData(totalLeft, blockSize int64, readers []io.ReadCloser, encoder Encoder, writer *io.PipeWriter) ([]byte, error) {
+func (b bucket) decodeEncodedData(totalLeft, blockSize int64, readers []io.ReadCloser, encoder encoder, writer *io.PipeWriter) ([]byte, error) {
 	var curBlockSize int64
 	if blockSize < totalLeft {
 		curBlockSize = blockSize
diff --git a/pkg/storage/donut/donut_encoder.go b/pkg/storage/donut/donut_encoder.go
index 18fa4cadb..1d62f4fdf 100644
--- a/pkg/storage/donut/donut_encoder.go
+++ b/pkg/storage/donut/donut_encoder.go
@@ -43,7 +43,7 @@ func getErasureTechnique(technique string) (encoding.Technique, error) {
 }
 
 // NewEncoder - instantiate a new encoder
-func NewEncoder(k, m uint8, technique string) (Encoder, error) {
+func NewEncoder(k, m uint8, technique string) (encoder, error) {
 	errParams := map[string]string{
 		"k":         strconv.FormatUint(uint64(k), 10),
 		"m":         strconv.FormatUint(uint64(m), 10),
@@ -52,11 +52,11 @@ func NewEncoder(k, m uint8, technique string) (Encoder, error) {
 	e := encoder{}
 	t, err := getErasureTechnique(technique)
 	if err != nil {
-		return nil, iodine.New(err, errParams)
+		return encoder{}, iodine.New(err, errParams)
 	}
 	params, err := encoding.ValidateParams(k, m, t)
 	if err != nil {
-		return nil, iodine.New(err, errParams)
+		return encoder{}, iodine.New(err, errParams)
 	}
 	e.encoder = encoding.NewErasure(params)
 	e.k = k
diff --git a/pkg/storage/donut/donut_internal_interfaces.go b/pkg/storage/donut/donut_internal_interfaces.go
deleted file mode 100644
index 3cb02240b..000000000
--- a/pkg/storage/donut/donut_internal_interfaces.go
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
- * Minimalist Object Storage, (C) 2015 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 donut
-
-import (
-	"io"
-	"os"
-)
-
-// Encoder interface
-type Encoder interface {
-	GetEncodedBlockLen(dataLength int) (int, error)
-	Encode(data []byte) (encodedData [][]byte, err error)
-	Decode(encodedData [][]byte, dataLength int) (data []byte, err error)
-}
-
-// Bucket interface
-type Bucket interface {
-	ListObjects() (map[string]Object, error)
-
-	GetObject(object string) (io.ReadCloser, int64, error)
-	PutObject(object string, contents io.Reader, expectedMD5Sum string, metadata map[string]string) (string, error)
-}
-
-// Object interface
-type Object interface {
-	GetObjectMetadata() (map[string]string, error)
-	GetDonutObjectMetadata() (map[string]string, error)
-}
-
-// Node interface
-type Node interface {
-	ListDisks() (map[string]Disk, error)
-	AttachDisk(disk Disk) error
-	DetachDisk(disk Disk) error
-
-	GetNodeName() string
-	SaveConfig() error
-	LoadConfig() error
-}
-
-// Disk interface
-type Disk interface {
-	MakeDir(dirname string) error
-
-	ListDir(dirname string) ([]os.FileInfo, error)
-	ListFiles(dirname string) ([]os.FileInfo, error)
-
-	MakeFile(path string) (*os.File, error)
-	OpenFile(path string) (*os.File, error)
-
-	GetPath() string
-	GetOrder() int
-	GetFSInfo() map[string]string
-}
diff --git a/pkg/storage/donut/donut_object.go b/pkg/storage/donut/donut_object.go
index 9cd466397..d394c132f 100644
--- a/pkg/storage/donut/donut_object.go
+++ b/pkg/storage/donut/donut_object.go
@@ -33,9 +33,9 @@ type object struct {
 }
 
 // NewObject - instantiate a new object
-func NewObject(objectName, p string) (Object, error) {
+func NewObject(objectName, p string) (object, error) {
 	if objectName == "" {
-		return nil, iodine.New(InvalidArgument{}, nil)
+		return object{}, iodine.New(InvalidArgument{}, nil)
 	}
 	o := object{}
 	o.name = objectName
diff --git a/pkg/storage/donut/donut_public_interfaces.go b/pkg/storage/donut/donut_public_interfaces.go
index 77e7cd7b5..5e513b7e8 100644
--- a/pkg/storage/donut/donut_public_interfaces.go
+++ b/pkg/storage/donut/donut_public_interfaces.go
@@ -16,7 +16,10 @@
 
 package donut
 
-import "io"
+import (
+	"io"
+	"os"
+)
 
 // Collection of Donut specification interfaces
 
@@ -28,16 +31,16 @@ type Donut interface {
 
 // ObjectStorage is a donut object storage interface
 type ObjectStorage interface {
-	// Storage service Operations
+	// Storage service operations
 	GetBucketMetadata(bucket string) (map[string]string, error)
 	SetBucketMetadata(bucket string, metadata map[string]string) error
 	ListBuckets() (map[string]map[string]string, error)
 	MakeBucket(bucket, acl string) error
 
-	// Bucket Operations
-	ListObjects(bucket, prefix, marker, delim string, maxKeys int) (result []string, prefixes []string, isTruncated bool, err error)
+	// Bucket operations
+	ListObjects(bucket, prefix, marker, delim string, maxKeys int) (objects []string, prefixes []string, isTruncated bool, err error)
 
-	// Object Operations
+	// Object operations
 	GetObject(bucket, object string) (io.ReadCloser, int64, error)
 	GetObjectMetadata(bucket, object string) (map[string]string, error)
 	PutObject(bucket, object, expectedMD5Sum string, reader io.ReadCloser, metadata map[string]string) (string, error)
@@ -55,3 +58,29 @@ type Management interface {
 	SaveConfig() error
 	LoadConfig() error
 }
+
+// Node interface for node management
+type Node interface {
+	ListDisks() (map[string]Disk, error)
+	AttachDisk(disk Disk) error
+	DetachDisk(disk Disk) error
+
+	GetNodeName() string
+	SaveConfig() error
+	LoadConfig() error
+}
+
+// Disk interface for disk management
+type Disk interface {
+	MakeDir(dirname string) error
+
+	ListDir(dirname string) ([]os.FileInfo, error)
+	ListFiles(dirname string) ([]os.FileInfo, error)
+
+	MakeFile(path string) (*os.File, error)
+	OpenFile(path string) (*os.File, error)
+
+	GetPath() string
+	GetOrder() int
+	GetFSInfo() map[string]string
+}