diff --git a/go/storage/volume.go b/go/storage/volume.go
index 124990341..44d80a6be 100644
--- a/go/storage/volume.go
+++ b/go/storage/volume.go
@@ -437,3 +437,17 @@ func (v *Volume) SetReplica(replica *ReplicaPlacement) error {
 	v.ReplicaPlacement = replica
 	return v.writeSuperBlock()
 }
+
+func (v *Volume) SetReadOnly(isReadOnly bool) error {
+	if isReadOnly == false {
+		if fi, e := v.dataFile.Stat(); e != nil {
+			return e
+		} else {
+			if fi.Mode()&0200 == 0 {
+				return errors.New(v.FileName() + ".dat is READONLY")
+			}
+		}
+	}
+	v.readOnly = isReadOnly
+	return nil
+}
diff --git a/go/storage/volume_vacuum.go b/go/storage/volume_vacuum.go
index 7377afdc9..a2b7cdf76 100644
--- a/go/storage/volume_vacuum.go
+++ b/go/storage/volume_vacuum.go
@@ -30,6 +30,7 @@ func (v *Volume) commitCompact() error {
 	glog.V(3).Infof("Got Committing lock...")
 	_ = v.dataFile.Close()
 	var e error
+
 	if e = os.Rename(v.FileName()+".cpd", v.FileName()+".dat"); e != nil {
 		return e
 	}
diff --git a/go/topology/topology.go b/go/topology/topology.go
index ee1477cd2..c329b5837 100644
--- a/go/topology/topology.go
+++ b/go/topology/topology.go
@@ -187,3 +187,18 @@ func (t *Topology) GetOrCreateDataCenter(dcName string) *DataCenter {
 	t.LinkChildNode(dc)
 	return dc
 }
+
+type DataNodeWalker func(dn *DataNode) (e error)
+
+func (t *Topology) WalkDataNode(walker DataNodeWalker) error {
+	for _, c := range t.Children() {
+		for _, rack := range c.(*DataCenter).Children() {
+			for _, dn := range rack.(*Rack).Children() {
+				if e := walker(dn.(*DataNode)); e != nil {
+					return e
+				}
+			}
+		}
+	}
+	return nil
+}
diff --git a/go/weed/weed_server/master_server.go b/go/weed/weed_server/master_server.go
index db70ca6b1..3cac1873a 100644
--- a/go/weed/weed_server/master_server.go
+++ b/go/weed/weed_server/master_server.go
@@ -71,6 +71,7 @@ func NewMasterServer(r *mux.Router, port int, metaFolder string,
 	r.HandleFunc("/vol/grow", ms.proxyToLeader(ms.guard.WhiteList(ms.volumeGrowHandler)))
 	r.HandleFunc("/vol/status", ms.proxyToLeader(ms.guard.WhiteList(ms.volumeStatusHandler)))
 	r.HandleFunc("/vol/vacuum", ms.proxyToLeader(ms.guard.WhiteList(ms.volumeVacuumHandler)))
+	r.HandleFunc("/replica/set", ms.proxyToLeader(ms.guard.WhiteList(ms.setReplicaHandler)))
 	r.HandleFunc("/submit", ms.guard.WhiteList(ms.submitFromMasterServerHandler))
 	r.HandleFunc("/delete", ms.guard.WhiteList(ms.deleteFromMasterServerHandler))
 	r.HandleFunc("/{fileId}", ms.proxyToLeader(ms.redirectHandler))
diff --git a/go/weed/weed_server/master_server_handlers_admin.go b/go/weed/weed_server/master_server_handlers_admin.go
index fb2b18983..72962517d 100644
--- a/go/weed/weed_server/master_server_handlers_admin.go
+++ b/go/weed/weed_server/master_server_handlers_admin.go
@@ -10,6 +10,9 @@ import (
 	"strconv"
 	"strings"
 
+	"net/url"
+	"sync"
+
 	"github.com/chrislusf/seaweedfs/go/glog"
 	"github.com/chrislusf/seaweedfs/go/operation"
 	"github.com/chrislusf/seaweedfs/go/storage"
@@ -184,3 +187,43 @@ func (ms *MasterServer) getVolumeGrowOption(r *http.Request) (*topology.VolumeGr
 	}
 	return volumeGrowOption, nil
 }
+
+//only proxy to each volume server
+func (ms *MasterServer) setReplicaHandler(w http.ResponseWriter, r *http.Request) {
+	r.ParseForm()
+	if _, e := storage.NewReplicaPlacementFromString(r.FormValue("replication")); e != nil {
+		writeJsonError(w, r, http.StatusBadRequest, e)
+		return
+	}
+	all, _ := strconv.ParseBool(r.FormValue("all"))
+	if !all && len(r.Form["volume"]) == 0 && len(r.Form["collection"]) == 0 {
+		writeJsonError(w, r, http.StatusBadRequest, errors.New("No available agrs found."))
+		return
+	}
+	result := make(map[string]interface{})
+	forms := r.Form
+	var wg sync.WaitGroup
+	ms.Topo.WalkDataNode(func(dn *topology.DataNode) (e error) {
+		wg.Add(1)
+		go func(server string, values url.Values) {
+			defer wg.Done()
+			jsonBlob, e := util.Post("http://"+server+"/admin/set_replica", values)
+			if e != nil {
+				result[server] = map[string]interface{}{
+					"error": e.Error() + " " + string(jsonBlob),
+				}
+			}
+			var ret interface{}
+			if e := json.Unmarshal(jsonBlob, ret); e == nil {
+				result[server] = ret
+			} else {
+				result[server] = map[string]interface{}{
+					"error": e.Error() + " " + string(jsonBlob),
+				}
+			}
+		}(dn.Url(), forms)
+		return nil
+	})
+	wg.Wait()
+	writeJson(w, r, http.StatusOK, result)
+}
diff --git a/go/weed/weed_server/volume_server_handlers_replicate.go b/go/weed/weed_server/volume_server_handlers_replicate.go
index 6efd2546c..cc421dc88 100644
--- a/go/weed/weed_server/volume_server_handlers_replicate.go
+++ b/go/weed/weed_server/volume_server_handlers_replicate.go
@@ -18,6 +18,9 @@ func (vs *VolumeServer) getVolumeCleanDataHandler(w http.ResponseWriter, r *http
 		http.Error(w, fmt.Sprintf("Not Found volume: %v", e), http.StatusBadRequest)
 		return
 	}
+	//set read only when replicating
+	v.SetReadOnly(true)
+	defer v.SetReadOnly(false)
 	cr, e := v.GetVolumeCleanReader()
 	if e != nil {
 		http.Error(w, fmt.Sprintf("Get volume clean reader: %v", e), http.StatusInternalServerError)
@@ -74,7 +77,7 @@ type VolumeOptError struct {
 
 func (vs *VolumeServer) setVolumeReplicaHandler(w http.ResponseWriter, r *http.Request) {
 	r.ParseForm()
-	replica, e := storage.NewReplicaPlacementFromString(r.FormValue("replica"))
+	replica, e := storage.NewReplicaPlacementFromString(r.FormValue("replication"))
 	if e != nil {
 		writeJsonError(w, r, http.StatusBadRequest, e)
 		return