diff --git a/weed-fs/src/cmd/weeds.go b/weed-fs/src/cmd/weeds.go
index 5e7e9477a..c4abd0288 100644
--- a/weed-fs/src/cmd/weeds.go
+++ b/weed-fs/src/cmd/weeds.go
@@ -8,7 +8,6 @@ import (
 	"http"
 	"json"
 	"log"
-	"rand"
 	"strconv"
 	"strings"
 )
@@ -23,7 +22,7 @@ var (
 
 func dirReadHandler(w http.ResponseWriter, r *http.Request) {
 	volumeId, _ := strconv.Atoui64(r.FormValue("volumeId"))
-	machine := mapper.Get(volumeId)
+	machine := mapper.Get(uint32(volumeId))
 	writeJson(w, r, machine.Server)
 }
 func dirWriteHandler(w http.ResponseWriter, r *http.Request) {
@@ -31,9 +30,7 @@ func dirWriteHandler(w http.ResponseWriter, r *http.Request) {
 	writeJson(w, r, machine)
 }
 func dirPickHandler(w http.ResponseWriter, r *http.Request) {
-    vid, machine := mapper.PickForWrite()
-    hashcode := rand.Uint32()
-    fid := strconv.Uitoa64(vid) + "," + strconv.Uitoa64(mapper.NextFileId())+","+strconv.Uitoa64(uint64(hashcode))
+    fid, machine := mapper.PickForWrite()
     writeJson(w, r, map[string]string{"fid":fid,"url":machine.Url})
 }
 func dirJoinHandler(w http.ResponseWriter, r *http.Request) {
diff --git a/weed-fs/src/pkg/directory/file_id.go b/weed-fs/src/pkg/directory/file_id.go
new file mode 100644
index 000000000..7cc91c3f6
--- /dev/null
+++ b/weed-fs/src/pkg/directory/file_id.go
@@ -0,0 +1,44 @@
+package directory
+
+import (
+	"encoding/hex"
+	"storage"
+	"strconv"
+	"strings"
+)
+
+type FileId struct {
+	VolumeId uint32
+	Key      uint64
+	Hashcode uint32
+}
+
+func NewFileId(VolumeId uint32, Key uint64, Hashcode uint32) *FileId {
+	return &FileId{VolumeId: VolumeId, Key: Key, Hashcode: Hashcode}
+}
+
+func ParseFileId(path string) *FileId {
+	a := strings.Split(path, ",")
+	if len(a) != 2 {
+		return nil
+	}
+	vid_string, key_hash_string := a[0], a[1]
+	key_hash_bytes, khe := hex.DecodeString(key_hash_string)
+	key_hash_len := len(key_hash_bytes)
+	if khe != nil || key_hash_len <= 4 {
+		return nil
+	}
+	vid, _ := strconv.Atoui64(vid_string)
+	key := storage.BytesToUint64(key_hash_bytes[0 : key_hash_len-4])
+	hash := storage.BytesToUint32(key_hash_bytes[key_hash_len-4 : key_hash_len])
+	return &FileId{VolumeId: uint32(vid), Key: key, Hashcode: hash}
+}
+func (n *FileId) String() string {
+	bytes := make([]byte, 12)
+	storage.Uint64toBytes(bytes[0:8], n.Key)
+	storage.Uint32toBytes(bytes[8:12], n.Hashcode)
+	nonzero_index := 0
+	for ; bytes[nonzero_index] == 0; nonzero_index++ {
+	}
+	return strconv.Uitoa64(uint64(n.VolumeId)) + "," + hex.EncodeToString(bytes[nonzero_index:])
+}
diff --git a/weed-fs/src/pkg/directory/file_id_test.go b/weed-fs/src/pkg/directory/file_id_test.go
new file mode 100644
index 000000000..0fdeb793a
--- /dev/null
+++ b/weed-fs/src/pkg/directory/file_id_test.go
@@ -0,0 +1,16 @@
+package directory
+
+import {
+    "testing"
+    "log"
+}
+func TestSerialDeserialization(t *testing.T) {
+    f1 := &FileId{VolumeId: 345, Key:8698, Hashcode: 23849095}
+    log.Println("vid", f1.VolumeId, "key", f1.Key, "hash", f1.Hashcode)
+
+    f2 := ParseFileId(t.String())
+
+    log.Println("vvid", f2.VolumeId, "vkey", f2.Key, "vhash", f2.Hashcode)
+
+    t.
+}
diff --git a/weed-fs/src/pkg/directory/volume_mapping.go b/weed-fs/src/pkg/directory/volume_mapping.go
index fa2ae62d3..3c10e1a78 100644
--- a/weed-fs/src/pkg/directory/volume_mapping.go
+++ b/weed-fs/src/pkg/directory/volume_mapping.go
@@ -32,10 +32,10 @@ type Mapper struct {
 
 	lock          sync.Mutex
 	Machines      []*Machine
-	vid2machineId map[uint64]int
+	vid2machineId map[uint32]int
 	Writers       []int // transient array of Writers volume id
 
-	GlobalVolumeSequence uint64
+	GlobalVolumeSequence uint32
 
 	FileIdSequence uint64
 	fileIdCounter  uint64
@@ -49,7 +49,7 @@ func NewMapper(dirname string, filename string, capacity int) (m *Mapper) {
 	m = &Mapper{dir: dirname, fileName: filename, capacity: capacity}
 	log.Println("Loading volume id to maching mapping:", path.Join(m.dir, m.fileName+".map"))
 	dataFile, e := os.OpenFile(path.Join(m.dir, m.fileName+".map"), os.O_RDONLY, 0644)
-	m.vid2machineId = make(map[uint64]int)
+	m.vid2machineId = make(map[uint32]int)
 	m.Writers = *new([]int)
 	if e != nil {
 		log.Println("Mapping File Read", e)
@@ -86,10 +86,10 @@ func NewMapper(dirname string, filename string, capacity int) (m *Mapper) {
 	}
 	return
 }
-func (m *Mapper) PickForWrite() (vid uint64, server MachineInfo) {
+func (m *Mapper) PickForWrite() (string, MachineInfo) {
 	machine := m.Machines[m.Writers[rand.Intn(len(m.Writers))]]
-	vid = machine.Volumes[rand.Intn(len(machine.Volumes))].Id
-	return vid, machine.Server
+	vid := machine.Volumes[rand.Intn(len(machine.Volumes))].Id
+	return NewFileId(vid,m.NextFileId(),rand.Uint32()).String(), machine.Server
 }
 func (m *Mapper) NextFileId() uint64 {
     if m.fileIdCounter <= 0 {
@@ -99,10 +99,10 @@ func (m *Mapper) NextFileId() uint64 {
 	m.fileIdCounter--
 	return m.FileIdSequence - m.fileIdCounter
 }
-func (m *Mapper) Get(vid uint64) *Machine {
+func (m *Mapper) Get(vid uint32) *Machine {
 	return m.Machines[m.vid2machineId[vid]]
 }
-func (m *Mapper) Add(machine Machine) []uint64 {
+func (m *Mapper) Add(machine Machine) []uint32 {
 	log.Println("Adding existing", machine.Server.Url, len(machine.Volumes), "volumes to dir", len(m.Machines))
 	log.Println("Adding      new ", machine.Server.Url, machine.Capacity-len(machine.Volumes), "volumes to dir", len(m.Machines))
 	//check existing machine, linearly
@@ -121,7 +121,7 @@ func (m *Mapper) Add(machine Machine) []uint64 {
 	}
 
 	//generate new volumes
-	vids := new([]uint64)
+	vids := new([]uint32)
 	for vid, i := m.GlobalVolumeSequence, len(machine.Volumes); i < machine.Capacity; i, vid = i+1, vid+1 {
 		newVolume := storage.VolumeInfo{Id: vid, Size: 0}
 		machine.Volumes = append(machine.Volumes, newVolume)
diff --git a/weed-fs/src/pkg/storage/needle.go b/weed-fs/src/pkg/storage/needle.go
index 8f014f73a..f60a15a5a 100644
--- a/weed-fs/src/pkg/storage/needle.go
+++ b/weed-fs/src/pkg/storage/needle.go
@@ -5,17 +5,16 @@ import (
 	"io/ioutil"
 	"http"
 	"log"
-	"strconv"
 	"strings"
 )
 
 type Needle struct {
-	Cookie       uint32  "random number to mitigate brute force lookups"
-	Key          uint64 "file id"
-	Size         uint32 "Data size"
-	Data         []byte "The actual file data"
-	Checksum     int32  "CRC32 to check integrity"
-	Padding      []byte "Aligned to 8 bytes"
+	Cookie   uint32 "random number to mitigate brute force lookups"
+	Key      uint64 "file id"
+	Size     uint32 "Data size"
+	Data     []byte "The actual file data"
+	Checksum int32  "CRC32 to check integrity"
+	Padding  []byte "Aligned to 8 bytes"
 }
 
 func NewNeedle(r *http.Request) (n *Needle) {
@@ -33,30 +32,31 @@ func NewNeedle(r *http.Request) (n *Needle) {
 	return
 }
 func (n *Needle) ParsePath(path string) {
-	a := strings.Split(path, "_")
-	log.Println("cookie", a[0], "key", a[1], "altKey", a[2])
-	cookie, _ := strconv.Atoui(a[0])
-	n.Cookie = uint32(cookie)
-	n.Key, _ = strconv.Atoui64(a[1])
+	if len(path) != 16 {
+		return
+	}
+    bytes := []byte(path)
+	n.Cookie = BytesToUint32(bytes[12:16])
+    n.Key = BytesToUint64(bytes[4:12])
 }
 func (n *Needle) Append(w io.Writer) {
 	header := make([]byte, 16)
-    uint32toBytes(header[0:4], n.Cookie)
-	uint64toBytes(header[4:12], n.Key)
+	Uint32toBytes(header[0:4], n.Cookie)
+	Uint64toBytes(header[4:12], n.Key)
 	n.Size = uint32(len(n.Data))
-	uint32toBytes(header[12:16], n.Size)
+	Uint32toBytes(header[12:16], n.Size)
 	w.Write(header)
 	w.Write(n.Data)
 	rest := 8 - ((n.Size + 16 + 4) % 8)
-	uint32toBytes(header[0:4], uint32(n.Checksum))
+	Uint32toBytes(header[0:4], uint32(n.Checksum))
 	w.Write(header[0 : rest+4])
 }
 func (n *Needle) Read(r io.Reader, size uint32) {
 	bytes := make([]byte, size+16+4)
 	r.Read(bytes)
-	n.Cookie = bytesToUint32(bytes[0:4])
-	n.Key = bytesToUint64(bytes[4:12])
-	n.Size = bytesToUint32(bytes[12:16])
+	n.Cookie = BytesToUint32(bytes[0:4])
+	n.Key = BytesToUint64(bytes[4:12])
+	n.Size = BytesToUint32(bytes[12:16])
 	n.Data = bytes[16 : 16+size]
-	n.Checksum = int32(bytesToUint32(bytes[16+size : 16+size+4]))
+	n.Checksum = int32(BytesToUint32(bytes[16+size : 16+size+4]))
 }
diff --git a/weed-fs/src/pkg/storage/store.go b/weed-fs/src/pkg/storage/store.go
index f3fc2862c..44e4d252e 100644
--- a/weed-fs/src/pkg/storage/store.go
+++ b/weed-fs/src/pkg/storage/store.go
@@ -17,7 +17,7 @@ type Store struct {
 	PublicServer string
 }
 type VolumeInfo struct {
-	Id   uint64
+	Id   uint32
 	Size int64
 }
 
@@ -35,7 +35,7 @@ func NewStore(port int, publicServer, dirname string, chunkSize, capacity int) (
 		if err != nil {
 			continue
 		}
-		s.volumes[id] = NewVolume(s.dir, id)
+		s.volumes[id] = NewVolume(s.dir, uint32(id))
 	}
 	log.Println("Store started on dir:", dirname, "with", len(s.volumes), "existing volumes")
 	log.Println("Expected capacity=", s.capacity, "volumes")
@@ -46,7 +46,7 @@ func (s *Store) Join(mserver string) {
 	stats := new([]*VolumeInfo)
 	for k, v := range s.volumes {
 		s := new(VolumeInfo)
-		s.Id, s.Size = k, v.Size()
+		s.Id, s.Size = uint32(k), v.Size()
 		*stats = append(*stats, s)
 	}
 	bytes, _ := json.Marshal(stats)
@@ -63,7 +63,7 @@ func (s *Store) Join(mserver string) {
 		e := json.Unmarshal(retString, newVids)
 		if e == nil {
 			for _, vid := range *newVids {
-				s.volumes[uint64(vid)] = NewVolume(s.dir, uint64(vid))
+				s.volumes[uint64(vid)] = NewVolume(s.dir, uint32(vid))
 				log.Println("Adding volume", vid)
 			}
 		}
diff --git a/weed-fs/src/pkg/storage/util.go b/weed-fs/src/pkg/storage/util.go
index 58a415bc0..48efeffe6 100644
--- a/weed-fs/src/pkg/storage/util.go
+++ b/weed-fs/src/pkg/storage/util.go
@@ -7,30 +7,32 @@ import (
     "log"
 )
 
-func bytesToUint64(b []byte)(v uint64){
-  for i :=uint(7);i>0;i-- {
+func BytesToUint64(b []byte)(v uint64){
+  length := uint(len(b))
+  for i :=uint(0);i<length-1;i++ {
     v += uint64(b[i])
     v <<= 8
   }
-  v+=uint64(b[0])
+  v+=uint64(b[length-1])
   return
 }
-func bytesToUint32(b []byte)(v uint32){
-  for i :=uint(3);i>0;i-- {
+func BytesToUint32(b []byte)(v uint32){
+  length := uint(len(b))
+  for i :=uint(0);i<length-1;i++ {
     v += uint32(b[i])
     v <<= 8
   }
-  v+=uint32(b[0])
+  v+=uint32(b[length-1])
   return
 }
-func uint64toBytes(b []byte, v uint64){
+func Uint64toBytes(b []byte, v uint64){
   for i :=uint(0);i<8;i++ {
-    b[i] = byte(v>>(i*8))
+    b[7-i] = byte(v>>(i*8))
   }
 }
-func uint32toBytes(b []byte, v uint32){
+func Uint32toBytes(b []byte, v uint32){
   for i :=uint(0);i<4;i++ {
-    b[i] = byte(v>>(i*8))
+    b[3-i] = byte(v>>(i*8))
   }
 }
 
diff --git a/weed-fs/src/pkg/storage/volume.go b/weed-fs/src/pkg/storage/volume.go
index dd1dff54e..457a93b5b 100644
--- a/weed-fs/src/pkg/storage/volume.go
+++ b/weed-fs/src/pkg/storage/volume.go
@@ -8,7 +8,7 @@ import (
 )
 
 type Volume struct {
-	Id                  uint64
+	Id                  uint32
 	dir                 string
 	dataFile, indexFile *os.File
 	nm                  *NeedleMap
@@ -16,10 +16,10 @@ type Volume struct {
 	accessChannel chan int
 }
 
-func NewVolume(dirname string, id uint64) (v *Volume) {
+func NewVolume(dirname string, id uint32) (v *Volume) {
 	var e os.Error
 	v = &Volume{dir:dirname,Id:id, nm:NewNeedleMap()}
-	fileName := strconv.Uitoa64(v.Id)
+	fileName := strconv.Uitoa64(uint64(v.Id))
 	v.dataFile, e = os.OpenFile(path.Join(v.dir,fileName+".dat"), os.O_RDWR|os.O_CREATE, 0644)
 	if e != nil {
 		log.Fatalf("New Volume [ERROR] %s\n", e)