diff --git a/weed/storage/needle/file_id.go b/weed/storage/needle/file_id.go
index 906877b8c..5dabb0f25 100644
--- a/weed/storage/needle/file_id.go
+++ b/weed/storage/needle/file_id.go
@@ -2,6 +2,8 @@ package needle
 
 import (
 	"encoding/hex"
+	"fmt"
+	"strings"
 
 	. "github.com/chrislusf/seaweedfs/weed/storage/types"
 )
@@ -20,6 +22,41 @@ func NewFileId(VolumeId VolumeId, key uint64, cookie uint32) *FileId {
 	return &FileId{VolumeId: VolumeId, Key: Uint64ToNeedleId(key), Cookie: Uint32ToCookie(cookie)}
 }
 
+// Deserialize the file id
+func ParseFileIdFromString(fid string) (*FileId, error) {
+	vid, needleKeyCookie, err := splitVolumeId(fid)
+	if err != nil {
+		return nil, err
+	}
+	volumeId, err := NewVolumeId(vid)
+	if err != nil {
+		return nil, err
+	}
+
+	nid, cookie, err := ParseNeedleIdCookie(needleKeyCookie)
+	if err != nil {
+		return nil, err
+	}
+	fileId := &FileId{VolumeId: volumeId, Key: nid, Cookie: cookie}
+	return fileId, nil
+}
+
+func (n *FileId) GetVolumeId() VolumeId {
+	return n.VolumeId
+}
+
+func (n *FileId) GetNeedleId() NeedleId {
+	return n.Key
+}
+
+func (n *FileId) GetCookie() Cookie {
+	return n.Cookie
+}
+
+func (n *FileId) GetNeedleIdCookie() string {
+	return formatNeedleIdCookie(n.Key, n.Cookie)
+}
+
 func (n *FileId) String() string {
 	return n.VolumeId.String() + "," + formatNeedleIdCookie(n.Key, n.Cookie)
 }
@@ -33,3 +70,12 @@ func formatNeedleIdCookie(key NeedleId, cookie Cookie) string {
 	}
 	return hex.EncodeToString(bytes[nonzero_index:])
 }
+
+// copied from operation/delete_content.go, to cut off cycle dependency
+func splitVolumeId(fid string) (vid string, key_cookie string, err error) {
+	commaIndex := strings.Index(fid, ",")
+	if commaIndex <= 0 {
+		return "", "", fmt.Errorf("wrong fid format")
+	}
+	return fid[:commaIndex], fid[commaIndex+1:], nil
+}
diff --git a/weed/storage/needle/file_id_test.go b/weed/storage/needle/file_id_test.go
new file mode 100644
index 000000000..a1a2c61fc
--- /dev/null
+++ b/weed/storage/needle/file_id_test.go
@@ -0,0 +1,55 @@
+package needle
+
+import (
+	"github.com/chrislusf/seaweedfs/weed/storage/types"
+	"testing"
+)
+
+func TestParseFileIdFromString(t *testing.T) {
+	fidStr1 := "100,12345678"
+	_, err := ParseFileIdFromString(fidStr1)
+	if err == nil {
+		t.Errorf("%s : KeyHash is too short", fidStr1)
+	}
+
+	fidStr1 = "100, 12345678"
+	_, err = ParseFileIdFromString(fidStr1)
+	if err == nil {
+		t.Errorf("%s : needlId invalid syntax", fidStr1)
+	}
+
+	fidStr1 = "100,123456789"
+	_, err = ParseFileIdFromString(fidStr1)
+	if err != nil {
+		t.Errorf("%s : should be OK", fidStr1)
+	}
+
+	var fileId *FileId
+	fidStr1 = "100,123456789012345678901234"
+	fileId, err = ParseFileIdFromString(fidStr1)
+	if err != nil {
+		t.Errorf("%s : should be OK", fidStr1)
+	}
+	if !(fileId.VolumeId == VolumeId(100) &&
+		fileId.Key == types.NeedleId(0x1234567890123456) &&
+		fileId.Cookie == types.Cookie(types.Uint32ToCookie(uint32(0x78901234)))) {
+		t.Errorf("src : %s, dest : %v", fidStr1, fileId)
+	}
+
+	fidStr1 = "100,abcd0000abcd"
+	fileId, err = ParseFileIdFromString(fidStr1)
+	if err != nil {
+		t.Errorf("%s : should be OK", fidStr1)
+	}
+	if !(fileId.VolumeId == VolumeId(100) &&
+		fileId.Key == types.NeedleId(0xabcd) &&
+		fileId.Cookie == types.Cookie(types.Uint32ToCookie(uint32(0xabcd)))) {
+		t.Errorf("src : %s, dest : %v", fidStr1, fileId)
+	}
+
+	fidStr1 = "100,1234567890123456789012345"
+	_, err = ParseFileIdFromString(fidStr1)
+	if err == nil {
+		t.Errorf("%s : needleId is too long", fidStr1)
+	}
+}
diff --git a/weed/storage/needle/volume_id.go b/weed/storage/needle/volume_id.go
index be56e42fa..3366c14bf 100644
--- a/weed/storage/needle/volume_id.go
+++ b/weed/storage/needle/volume_id.go
@@ -10,9 +10,9 @@ func NewVolumeId(vid string) (VolumeId, error) {
 	volumeId, err := strconv.ParseUint(vid, 10, 64)
 	return VolumeId(volumeId), err
 }
-func (vid *VolumeId) String() string {
-	return strconv.FormatUint(uint64(*vid), 10)
+func (vid VolumeId) String() string {
+	return strconv.FormatUint(uint64(vid), 10)
 }
-func (vid *VolumeId) Next() VolumeId {
-	return VolumeId(uint32(*vid) + 1)
+func (vid VolumeId) Next() VolumeId {
+	return VolumeId(uint32(vid) + 1)
 }
diff --git a/weed/storage/needle/volume_id_test.go b/weed/storage/needle/volume_id_test.go
new file mode 100644
index 000000000..c1c426989
--- /dev/null
+++ b/weed/storage/needle/volume_id_test.go
@@ -0,0 +1,45 @@
+package needle
+
+import "testing"
+
+func TestNewVolumeId(t *testing.T) {
+	if _,err := NewVolumeId("1"); err != nil {
+		t.Error(err)
+	}
+
+	if _, err := NewVolumeId("a");err != nil {
+		t.Logf("a is not legal volume id, %v", err)
+	}
+}
+
+func TestVolumeId_String(t *testing.T) {
+	if str := VolumeId(10).String(); str != "10" {
+		t.Errorf("to string failed")
+	}
+
+	vid := VolumeId(11)
+	if str := vid.String(); str != "11" {
+		t.Errorf("to string failed")
+	}
+
+	pvid := &vid
+	if str := pvid.String(); str != "11" {
+		t.Errorf("to string failed")
+	}
+}
+
+func TestVolumeId_Next(t *testing.T) {
+	if vid := VolumeId(10).Next(); vid != VolumeId(11) {
+		t.Errorf("get next volume id failed")
+	}
+
+	vid := VolumeId(11)
+	if new := vid.Next(); new != 12 {
+		t.Errorf("get next volume id failed")
+	}
+
+	pvid := &vid
+	if new := pvid.Next(); new != 12 {
+		t.Errorf("get next volume id failed")
+	}
+}
\ No newline at end of file