diff --git a/.travis.yml b/.travis.yml
index 79cec6d8a..1a2ae20ed 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,7 @@
 language: go
 go: 
  - 1.3
- - release
+ - 1.4.1
  - tip
 
 before_install:
diff --git a/docs/usecases.rst b/docs/usecases.rst
index 8a9a6d44a..ac0a2d0b3 100644
--- a/docs/usecases.rst
+++ b/docs/usecases.rst
@@ -52,4 +52,63 @@ However, if blocking servicing port is not feasible or trivial, a white list opt
 
 	weed master -whiteList="::1,127.0.0.1"
 	weed volume -whiteList="::1,127.0.0.1"
-	# "::1" is for IP v6 localhost.
\ No newline at end of file
+	# "::1" is for IP v6 localhost.
+
+
+Data Migration Example
+#############################
+
+.. code-block:: bash
+
+	weed master -mdir="/tmp/mdata" -defaultReplication="001" -ip="localhost" -port=9334
+	weed volume -dir=/tmp/vol1/ -mserver="localhost:9334" -ip="localhost" -port=8081
+	weed volume -dir=/tmp/vol2/ -mserver="localhost:9334" -ip="localhost" -port=8082
+	weed volume -dir=/tmp/vol3/ -mserver="localhost:9334" -ip="localhost" -port=8083
+
+.. code-block:: bash
+
+	ls vol1 vol2 vol3
+	vol1:
+	1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 5.dat 5.idx
+	vol2:
+	2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 6.dat 6.idx
+	vol3:
+	1.dat 1.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
+
+stop all of them
+
+move vol3/* to vol1 and vol2
+
+it is ok to move x.dat and x.idx from one volumeserver to another volumeserver, 
+because they are exactly the same. 
+it can be checked by md5.
+
+.. code-block:: bash
+
+	md5 vol1/1.dat vol2/1.dat
+	MD5 (vol1/1.dat) = c1a49a0ee550b44fef9f8ae9e55215c7
+	MD5 (vol2/1.dat) = c1a49a0ee550b44fef9f8ae9e55215c7
+	md5 vol1/1.idx vol2/1.idx
+	MD5 (vol1/1.idx) = b9edc95795dfb3b0f9063c9cc9ba8095
+	MD5 (vol2/1.idx) = b9edc95795dfb3b0f9063c9cc9ba8095
+
+.. code-block:: bash
+
+	ls vol1 vol2 vol3
+	vol1:
+	1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
+	vol2:
+	1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
+	vol3:
+
+start
+
+.. code-block:: bash
+
+	weed master -mdir="/tmp/mdata" -defaultReplication="001" -ip="localhost" -port=9334
+	weed volume -dir=/tmp/vol1/ -mserver="localhost:9334" -ip="localhost" -port=8081
+	weed volume -dir=/tmp/vol2/ -mserver="localhost:9334" -ip="localhost" -port=8082
+
+so we finished moving data of localhost:8083 to localhost:8081/localhost:8082 
+
+
diff --git a/go/operation/delete_content.go b/go/operation/delete_content.go
index 416a852b3..064cc8df9 100644
--- a/go/operation/delete_content.go
+++ b/go/operation/delete_content.go
@@ -66,11 +66,11 @@ func DeleteFiles(master string, fileIds []string) (*DeleteFilesResult, error) {
 			continue
 		}
 		for _, location := range result.Locations {
-			if _, ok := server_to_fileIds[location.PublicUrl]; !ok {
-				server_to_fileIds[location.PublicUrl] = make([]string, 0)
+			if _, ok := server_to_fileIds[location.Url]; !ok {
+				server_to_fileIds[location.Url] = make([]string, 0)
 			}
-			server_to_fileIds[location.PublicUrl] = append(
-				server_to_fileIds[location.PublicUrl], vid_to_fileIds[vid]...)
+			server_to_fileIds[location.Url] = append(
+				server_to_fileIds[location.Url], vid_to_fileIds[vid]...)
 		}
 	}
 
diff --git a/go/operation/lookup.go b/go/operation/lookup.go
index c05eb1d2b..8156c9779 100644
--- a/go/operation/lookup.go
+++ b/go/operation/lookup.go
@@ -72,7 +72,7 @@ func LookupFileId(server string, fileId string) (fullUrl string, err error) {
 	if len(lookup.Locations) == 0 {
 		return "", errors.New("File Not Found")
 	}
-	return "http://" + lookup.Locations[rand.Intn(len(lookup.Locations))].PublicUrl + "/" + fileId, nil
+	return "http://" + lookup.Locations[rand.Intn(len(lookup.Locations))].Url + "/" + fileId, nil
 }
 
 // LookupVolumeIds find volume locations by cache and actual lookup
diff --git a/go/operation/submit.go b/go/operation/submit.go
index 62db46617..3ab6d78d9 100644
--- a/go/operation/submit.go
+++ b/go/operation/submit.go
@@ -137,7 +137,7 @@ func upload_one_chunk(filename string, reader io.Reader, master, replication str
 	if err != nil {
 		return "", 0, err
 	}
-	fileUrl, fid := "http://"+ret.PublicUrl+"/"+ret.Fid, ret.Fid
+	fileUrl, fid := "http://"+ret.Url+"/"+ret.Fid, ret.Fid
 	glog.V(4).Info("Uploading part ", filename, " to ", fileUrl, "...")
 	uploadResult, uploadError := Upload(fileUrl, filename, reader, false, "application/octet-stream")
 	if uploadError != nil {
diff --git a/go/weed/benchmark.go b/go/weed/benchmark.go
index f4f0b1874..04ab4307d 100644
--- a/go/weed/benchmark.go
+++ b/go/weed/benchmark.go
@@ -203,7 +203,7 @@ func writeFiles(idChan chan int, fileIdLineChan chan string, s *stat) {
 		fileSize := int64(*b.fileSize + rand.Intn(64))
 		fp := &operation.FilePart{Reader: &FakeReader{id: uint64(id), size: fileSize}, FileSize: fileSize}
 		if assignResult, err := operation.Assign(*b.server, 1, "", *b.collection, ""); err == nil {
-			fp.Server, fp.Fid, fp.Collection = assignResult.PublicUrl, assignResult.Fid, *b.collection
+			fp.Server, fp.Fid, fp.Collection = assignResult.Url, assignResult.Fid, *b.collection
 			if _, err := fp.Upload(0, *b.server); err == nil {
 				if rand.Intn(100) < *b.deletePercentage {
 					s.total++
@@ -251,7 +251,7 @@ func readFiles(fileIdLineChan chan string, s *stat) {
 			if _, now_ok := b.vid2server[vid]; !now_ok {
 				if ret, err := operation.Lookup(*b.server, vid); err == nil {
 					if len(ret.Locations) > 0 {
-						server = ret.Locations[0].PublicUrl
+						server = ret.Locations[0].Url
 						b.vid2server[vid] = server
 					}
 				}
diff --git a/go/weed/master.go b/go/weed/master.go
index 13f6d7c43..af63d8c22 100644
--- a/go/weed/master.go
+++ b/go/weed/master.go
@@ -31,7 +31,6 @@ var (
 	mport                   = cmdMaster.Flag.Int("port", 9333, "http listen port")
 	masterIp                = cmdMaster.Flag.String("ip", "", "master listening ip address, default to listen on all network interfaces")
 	masterBindIp            = cmdMaster.Flag.String("ip.bind", "0.0.0.0", "ip address to bind to")
-	mPublicIp               = cmdMaster.Flag.String("publicIp", "", "peer accessible <ip>|<server_name>")
 	metaFolder              = cmdMaster.Flag.String("mdir", os.TempDir(), "data directory to store meta data")
 	masterPeers             = cmdMaster.Flag.String("peers", "", "other master nodes in comma separated ip:port list")
 	volumeSizeLimitMB       = cmdMaster.Flag.Uint("volumeSizeLimitMB", 30*1000, "Master stops directing writes to oversized volumes.")
@@ -76,19 +75,15 @@ func runMaster(cmd *Command, args []string) bool {
 
 	go func() {
 		time.Sleep(100 * time.Millisecond)
-		if *mPublicIp == "" {
-			if *masterIp == "" {
-				*mPublicIp = "localhost"
-			} else {
-				*mPublicIp = *masterIp
-			}
+		if *masterIp == "" {
+			*masterIp = "localhost"
 		}
-		myPublicMasterAddress := *mPublicIp + ":" + strconv.Itoa(*mport)
+		myMasterAddress := *masterIp + ":" + strconv.Itoa(*mport)
 		var peers []string
 		if *masterPeers != "" {
 			peers = strings.Split(*masterPeers, ",")
 		}
-		raftServer := weed_server.NewRaftServer(r, peers, myPublicMasterAddress, *metaFolder, ms.Topo, *mpulse)
+		raftServer := weed_server.NewRaftServer(r, peers, myMasterAddress, *metaFolder, ms.Topo, *mpulse)
 		ms.SetRaftServer(raftServer)
 	}()
 
diff --git a/go/weed/server.go b/go/weed/server.go
index 16b809c53..b779033cb 100644
--- a/go/weed/server.go
+++ b/go/weed/server.go
@@ -48,7 +48,7 @@ var cmdServer = &Command{
 
 var (
 	serverIp                      = cmdServer.Flag.String("ip", "", "ip or server name")
-	serverPublicIp                = cmdServer.Flag.String("publicIp", "", "ip or server name")
+	serverPublicUrl               = cmdServer.Flag.String("publicUrl", "", "publicly accessible address")
 	serverBindIp                  = cmdServer.Flag.String("ip.bind", "0.0.0.0", "ip address to bind to")
 	serverMaxCpu                  = cmdServer.Flag.Int("maxCpu", 0, "maximum number of CPUs. 0 means all available CPUs")
 	serverTimeout                 = cmdServer.Flag.Int("idleTimeout", 10, "connection idle seconds")
@@ -99,19 +99,15 @@ func runServer(cmd *Command, args []string) bool {
 		defer pprof.StopCPUProfile()
 	}
 
-	if *serverPublicIp == "" {
-		if *serverIp == "" {
-			*serverPublicIp = "localhost"
-		} else {
-			*serverPublicIp = *serverIp
-		}
+	if *serverIp == "" {
+		*serverIp = "localhost"
 	}
 
 	if *filerOptions.redirectOnRead {
 		*isStartingFiler = true
 	}
 
-	*filerOptions.master = *serverPublicIp + ":" + strconv.Itoa(*masterPort)
+	*filerOptions.master = *serverIp + ":" + strconv.Itoa(*masterPort)
 
 	if *filerOptions.defaultReplicaPlacement == "" {
 		*filerOptions.defaultReplicaPlacement = *masterDefaultReplicaPlacement
@@ -144,9 +140,11 @@ func runServer(cmd *Command, args []string) bool {
 	if *masterMetaFolder == "" {
 		*masterMetaFolder = folders[0]
 	}
-	if *filerOptions.dir == "" {
-		*filerOptions.dir = *masterMetaFolder + "/filer"
-		os.MkdirAll(*filerOptions.dir, 0700)
+	if *isStartingFiler {
+		if *filerOptions.dir == "" {
+			*filerOptions.dir = *masterMetaFolder + "/filer"
+			os.MkdirAll(*filerOptions.dir, 0700)
+		}
 	}
 	if err := util.TestFolderWritable(*masterMetaFolder); err != nil {
 		glog.Fatalf("Check Meta Folder (-mdir=\"%s\") Writable: %s", *masterMetaFolder, err)
@@ -207,7 +205,7 @@ func runServer(cmd *Command, args []string) bool {
 		go func() {
 			raftWaitForMaster.Wait()
 			time.Sleep(100 * time.Millisecond)
-			myAddress := *serverPublicIp + ":" + strconv.Itoa(*masterPort)
+			myAddress := *serverIp + ":" + strconv.Itoa(*masterPort)
 			var peers []string
 			if *serverPeers != "" {
 				peers = strings.Split(*serverPeers, ",")
@@ -227,7 +225,7 @@ func runServer(cmd *Command, args []string) bool {
 	time.Sleep(100 * time.Millisecond)
 	r := http.NewServeMux()
 	volumeServer := weed_server.NewVolumeServer(r, r,
-		*serverIp, *volumePort, *volumeAdminPort, *serverPublicIp,
+		*serverIp, *volumePort, *volumeAdminPort, *serverPublicUrl,
 		folders, maxCounts,
 		*serverIp+":"+strconv.Itoa(*masterPort), *volumePulse, *serverDataCenter, *serverRack,
 		serverWhiteList, *volumeFixJpgOrientation,
diff --git a/go/weed/volume.go b/go/weed/volume.go
index df1d603ac..df3974c8c 100644
--- a/go/weed/volume.go
+++ b/go/weed/volume.go
@@ -23,7 +23,7 @@ type VolumeServerOptions struct {
 	folders               []string
 	folderMaxLimits       []int
 	ip                    *string
-	publicIp              *string
+	publicUrl             *string
 	bindIp                *string
 	master                *string
 	pulseSeconds          *int
@@ -40,7 +40,7 @@ func init() {
 	v.port = cmdVolume.Flag.Int("port", 8080, "http listen port")
 	v.adminPort = cmdVolume.Flag.Int("port.admin", 0, "admin port to talk with master and other volume servers")
 	v.ip = cmdVolume.Flag.String("ip", "", "ip or server name")
-	v.publicIp = cmdVolume.Flag.String("publicIp", "", "Publicly accessible <ip|server_name>")
+	v.publicUrl = cmdVolume.Flag.String("publicUrl", "", "Publicly accessible address")
 	v.bindIp = cmdVolume.Flag.String("ip.bind", "0.0.0.0", "ip address to bind to")
 	v.master = cmdVolume.Flag.String("mserver", "localhost:9333", "master server location")
 	v.pulseSeconds = cmdVolume.Flag.Int("pulseSeconds", 5, "number of seconds between heartbeats, must be smaller than or equal to the master's setting")
@@ -95,14 +95,8 @@ func runVolume(cmd *Command, args []string) bool {
 		v.whiteList = strings.Split(*volumeWhiteListOption, ",")
 	}
 
-	//derive default public ip address
-	if *v.publicIp == "" {
-		if *v.ip == "" {
-			*v.ip = "127.0.0.1"
-			*v.publicIp = "localhost"
-		} else {
-			*v.publicIp = *v.ip
-		}
+	if *v.ip == "" {
+		*v.ip = "127.0.0.1"
 	}
 
 	if *v.adminPort == 0 {
@@ -117,7 +111,7 @@ func runVolume(cmd *Command, args []string) bool {
 	}
 
 	volumeServer := weed_server.NewVolumeServer(publicMux, adminMux,
-		*v.ip, *v.port, *v.adminPort, *v.publicIp,
+		*v.ip, *v.port, *v.adminPort, *v.publicUrl,
 		v.folders, v.folderMaxLimits,
 		*v.master, *v.pulseSeconds, *v.dataCenter, *v.rack,
 		v.whiteList,
diff --git a/go/weed/weed_server/common.go b/go/weed/weed_server/common.go
index d259aa660..a2d93c246 100644
--- a/go/weed/weed_server/common.go
+++ b/go/weed/weed_server/common.go
@@ -96,7 +96,7 @@ func submitForClientHandler(w http.ResponseWriter, r *http.Request, masterUrl st
 		return
 	}
 
-	url := "http://" + assignResult.PublicUrl + "/" + assignResult.Fid
+	url := "http://" + assignResult.Url + "/" + assignResult.Fid
 	if lastModified != 0 {
 		url = url + "?ts=" + strconv.FormatUint(lastModified, 10)
 	}
diff --git a/go/weed/weed_server/filer_server_handlers.go b/go/weed/weed_server/filer_server_handlers.go
index 0811b7973..ac894771a 100644
--- a/go/weed/weed_server/filer_server_handlers.go
+++ b/go/weed/weed_server/filer_server_handlers.go
@@ -80,7 +80,7 @@ func (fs *FilerServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request,
 		w.WriteHeader(http.StatusNotFound)
 		return
 	}
-	urlLocation := lookup.Locations[rand.Intn(len(lookup.Locations))].PublicUrl
+	urlLocation := lookup.Locations[rand.Intn(len(lookup.Locations))].Url
 	urlString := "http://" + urlLocation + "/" + fileId
 	if fs.redirectOnRead {
 		http.Redirect(w, r, urlString, http.StatusFound)
@@ -126,7 +126,7 @@ func (fs *FilerServer) PostHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	u, _ := url.Parse("http://" + assignResult.PublicUrl + "/" + assignResult.Fid)
+	u, _ := url.Parse("http://" + assignResult.Url + "/" + assignResult.Fid)
 	glog.V(4).Infoln("post to", u)
 	request := &http.Request{
 		Method:        r.Method,
diff --git a/go/weed/weed_server/master_server_handlers_admin.go b/go/weed/weed_server/master_server_handlers_admin.go
index 4d304efcb..33e45afd2 100644
--- a/go/weed/weed_server/master_server_handlers_admin.go
+++ b/go/weed/weed_server/master_server_handlers_admin.go
@@ -119,7 +119,7 @@ func (ms *MasterServer) redirectHandler(w http.ResponseWriter, r *http.Request)
 	}
 	machines := ms.Topo.Lookup("", volumeId)
 	if machines != nil && len(machines) > 0 {
-		http.Redirect(w, r, "http://"+machines[0].PublicUrl+r.URL.Path, http.StatusMovedPermanently)
+		http.Redirect(w, r, "http://"+machines[0].Url()+r.URL.Path, http.StatusMovedPermanently)
 	} else {
 		writeJsonError(w, r, http.StatusNotFound, fmt.Errorf("volume id %d not found.", volumeId))
 	}
diff --git a/go/weed/weed_server/volume_server.go b/go/weed/weed_server/volume_server.go
index 8846c4794..f3ad2974d 100644
--- a/go/weed/weed_server/volume_server.go
+++ b/go/weed/weed_server/volume_server.go
@@ -3,7 +3,6 @@ package weed_server
 import (
 	"math/rand"
 	"net/http"
-	"strconv"
 	"time"
 
 	"github.com/chrislusf/weed-fs/go/glog"
@@ -23,13 +22,12 @@ type VolumeServer struct {
 }
 
 func NewVolumeServer(publicMux, adminMux *http.ServeMux, ip string,
-	port, adminPort int, publicIp string,
+	port, adminPort int, publicUrl string,
 	folders []string, maxCounts []int,
 	masterNode string, pulseSeconds int,
 	dataCenter string, rack string,
 	whiteList []string,
 	fixJpgOrientation bool) *VolumeServer {
-	publicUrl := publicIp + ":" + strconv.Itoa(port)
 	vs := &VolumeServer{
 		masterNode:        masterNode,
 		pulseSeconds:      pulseSeconds,
diff --git a/go/weed/weed_server/volume_server_handlers.go b/go/weed/weed_server/volume_server_handlers.go
index 6b47ee84d..c2c9e8523 100644
--- a/go/weed/weed_server/volume_server_handlers.go
+++ b/go/weed/weed_server/volume_server_handlers.go
@@ -61,7 +61,7 @@ func (vs *VolumeServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request)
 		lookupResult, err := operation.Lookup(vs.masterNode, volumeId.String())
 		glog.V(2).Infoln("volume", volumeId, "found on", lookupResult, "error", err)
 		if err == nil && len(lookupResult.Locations) > 0 {
-			http.Redirect(w, r, "http://"+lookupResult.Locations[0].PublicUrl+r.URL.Path, http.StatusMovedPermanently)
+			http.Redirect(w, r, "http://"+lookupResult.Locations[0].Url+r.URL.Path, http.StatusMovedPermanently)
 		} else {
 			glog.V(2).Infoln("lookup error:", err, r.URL.Path)
 			w.WriteHeader(http.StatusNotFound)