diff --git a/weed/storage/needle/compact_map_perf_test.go b/weed/storage/needle/compact_map_perf_test.go
index 59dd7f7f0..7908e8d1d 100644
--- a/weed/storage/needle/compact_map_perf_test.go
+++ b/weed/storage/needle/compact_map_perf_test.go
@@ -30,9 +30,10 @@ func loadNewNeedleMap(file *os.File) {
 	}
 	for count > 0 && e == nil {
 		for i := 0; i < count; i += 16 {
-			key := util.BytesToUint64(bytes[i: i+8])
-			offset := util.BytesToUint32(bytes[i+8: i+12])
-			size := util.BytesToUint32(bytes[i+12: i+16])
+			key := BytesToNeedleId(bytes[i:i+NeedleIdSize])
+			offset := BytesToOffset(bytes[i+NeedleIdSize:i+NeedleIdSize+OffsetSize])
+			size := util.BytesToUint32(bytes[i+NeedleIdSize+OffsetSize:i+NeedleIdSize+OffsetSize+SizeSize])
+
 			if offset > 0 {
 				m.Set(NeedleId(key), offset, size)
 			} else {
diff --git a/weed/storage/needle/compact_map_test.go b/weed/storage/needle/compact_map_test.go
index 3c5c90fff..11d98eab3 100644
--- a/weed/storage/needle/compact_map_test.go
+++ b/weed/storage/needle/compact_map_test.go
@@ -22,7 +22,7 @@ func TestIssue52(t *testing.T) {
 func TestXYZ(t *testing.T) {
 	m := NewCompactMap()
 	for i := uint32(0); i < 100*batch; i += 2 {
-		m.Set(NeedleId(i), i, i)
+		m.Set(NeedleId(i), Offset(i), i)
 	}
 
 	for i := uint32(0); i < 100*batch; i += 37 {
@@ -30,7 +30,7 @@ func TestXYZ(t *testing.T) {
 	}
 
 	for i := uint32(0); i < 10*batch; i += 3 {
-		m.Set(NeedleId(i), i+11, i+5)
+		m.Set(NeedleId(i), Offset(i+11), i+5)
 	}
 
 	//	for i := uint32(0); i < 100; i++ {
diff --git a/weed/storage/needle_map_metric_test.go b/weed/storage/needle_map_metric_test.go
index 0be2e1d7c..400e655a7 100644
--- a/weed/storage/needle_map_metric_test.go
+++ b/weed/storage/needle_map_metric_test.go
@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"math/rand"
 	"github.com/chrislusf/seaweedfs/weed/glog"
+	. "github.com/chrislusf/seaweedfs/weed/storage/types"
 )
 
 func TestFastLoadingNeedleMapMetrics(t *testing.T) {
@@ -13,9 +14,9 @@ func TestFastLoadingNeedleMapMetrics(t *testing.T) {
 	nm := NewBtreeNeedleMap(idxFile)
 
 	for i := 0; i < 10000; i++ {
-		nm.Put(uint64(i+1), uint32(0), uint32(1))
+		nm.Put(Uint64ToNeedleId(uint64(i+1)), Uint32ToOffset(uint32(0)), uint32(1))
 		if rand.Float32() < 0.2 {
-			nm.Delete(uint64(rand.Int63n(int64(i))+1), uint32(0))
+			nm.Delete(Uint64ToNeedleId(uint64(rand.Int63n(int64(i))+1)), Uint32ToOffset(uint32(0)))
 		}
 	}
 
diff --git a/weed/storage/needle_test.go b/weed/storage/needle_test.go
index f2b578aa6..4dce3f123 100644
--- a/weed/storage/needle_test.go
+++ b/weed/storage/needle_test.go
@@ -1,12 +1,15 @@
 package storage
 
-import "testing"
+import (
+	"testing"
+	"github.com/chrislusf/seaweedfs/weed/storage/types"
+)
 
 func TestParseKeyHash(t *testing.T) {
 	testcases := []struct {
 		KeyHash string
-		ID      uint64
-		Cookie  uint32
+		ID      types.NeedleId
+		Cookie  types.Cookie
 		Err     bool
 	}{
 		// normal
diff --git a/weed/storage/types/needle_types.go b/weed/storage/types/needle_types.go
index 6e092f100..0c0b6a7a3 100644
--- a/weed/storage/types/needle_types.go
+++ b/weed/storage/types/needle_types.go
@@ -54,6 +54,10 @@ func OffsetToBytes(bytes []byte, offset Offset) {
 	util.Uint32toBytes(bytes, uint32(offset))
 }
 
+func Uint32ToOffset(offset uint32) (Offset) {
+	return Offset(offset)
+}
+
 func BytesToOffset(bytes []byte) (Offset) {
 	return Offset(util.BytesToUint32(bytes[0:4]))
 }
diff --git a/weed/storage/volume_vacuum_test.go b/weed/storage/volume_vacuum_test.go
index c74c24b16..896540621 100644
--- a/weed/storage/volume_vacuum_test.go
+++ b/weed/storage/volume_vacuum_test.go
@@ -5,6 +5,7 @@ import (
 	"math/rand"
 	"os"
 	"testing"
+	"github.com/chrislusf/seaweedfs/weed/storage/types"
 )
 
 /*
@@ -153,12 +154,12 @@ func newRandomNeedle(id uint64) *Needle {
 	rand.Read(n.Data)
 
 	n.Checksum = NewCRC(n.Data)
-	n.Id = id
+	n.Id = types.Uint64ToNeedleId(id)
 	return n
 }
 
 func newEmptyNeedle(id uint64) *Needle {
 	n := new(Needle)
-	n.Id = id
+	n.Id = types.Uint64ToNeedleId(id)
 	return n
 }
diff --git a/weed/tools/read_index.go b/weed/tools/read_index.go
index 642ff786b..d53f489ea 100644
--- a/weed/tools/read_index.go
+++ b/weed/tools/read_index.go
@@ -7,6 +7,7 @@ import (
 	"os"
 
 	"github.com/chrislusf/seaweedfs/weed/storage"
+	"github.com/chrislusf/seaweedfs/weed/storage/types"
 )
 
 var (
@@ -21,8 +22,8 @@ func main() {
 	}
 	defer indexFile.Close()
 
-	storage.WalkIndexFile(indexFile, func(key uint64, offset, size uint32) error {
-		fmt.Printf("key %d, offset %d, size %d, nextOffset %d\n", key, offset*8, size, offset*8+size)
+	storage.WalkIndexFile(indexFile, func(key types.NeedleId, offset types.Offset, size uint32) error {
+		fmt.Printf("key %d, offset %d, size %d, nextOffset %d\n", key, offset*8, size, int64(offset)*types.NeedlePaddingSize+int64(size))
 		return nil
 	})
 }