diff --git a/weed/server/volume_grpc_tail.go b/weed/server/volume_grpc_tail.go
index 820c28a1d..667131e9f 100644
--- a/weed/server/volume_grpc_tail.go
+++ b/weed/server/volume_grpc_tail.go
@@ -111,7 +111,7 @@ func (vs *VolumeServer) VolumeTailReceiver(ctx context.Context, req *volume_serv
 	defer glog.V(1).Infof("receive tailing volume %d finished", v.Id)
 
 	return resp, operation.TailVolumeFromSource(req.SourceVolumeServer, vs.grpcDialOption, v.Id, req.SinceNs, int(req.IdleTimeoutSeconds), func(n *needle.Needle) error {
-		_, err := vs.store.Write(v.Id, n)
+		_, _, err := vs.store.Write(v.Id, n)
 		return err
 	})
 
diff --git a/weed/server/volume_server_handlers_write.go b/weed/server/volume_server_handlers_write.go
index 45c868c33..188d88ddf 100644
--- a/weed/server/volume_server_handlers_write.go
+++ b/weed/server/volume_server_handlers_write.go
@@ -41,11 +41,14 @@ func (vs *VolumeServer) PostHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	ret := operation.UploadResult{}
-	_, errorStatus := topology.ReplicatedWrite(vs.GetMaster(), vs.store, volumeId, needle, r)
+	_, isUnchanged, writeError := topology.ReplicatedWrite(vs.GetMaster(), vs.store, volumeId, needle, r)
 	httpStatus := http.StatusCreated
-	if errorStatus != "" {
+	if isUnchanged {
+		httpStatus = http.StatusNotModified
+	}
+	if writeError != nil {
 		httpStatus = http.StatusInternalServerError
-		ret.Error = errorStatus
+		ret.Error = writeError.Error()
 	}
 	if needle.HasName() {
 		ret.Name = string(needle.Name)
diff --git a/weed/storage/store.go b/weed/storage/store.go
index b870cee4e..3b2bb2c34 100644
--- a/weed/storage/store.go
+++ b/weed/storage/store.go
@@ -192,7 +192,7 @@ func (s *Store) Close() {
 	}
 }
 
-func (s *Store) Write(i needle.VolumeId, n *needle.Needle) (size uint32, err error) {
+func (s *Store) Write(i needle.VolumeId, n *needle.Needle) (size uint32, isUnchanged bool, err error) {
 	if v := s.findVolume(i); v != nil {
 		if v.readOnly {
 			err = fmt.Errorf("Volume %d is read only", i)
@@ -200,7 +200,7 @@ func (s *Store) Write(i needle.VolumeId, n *needle.Needle) (size uint32, err err
 		}
 		// TODO: count needle size ahead
 		if MaxPossibleVolumeSize >= v.ContentSize()+uint64(size) {
-			_, size, err = v.writeNeedle(n)
+			_, size, isUnchanged, err = v.writeNeedle(n)
 		} else {
 			err = fmt.Errorf("Volume Size Limit %d Exceeded! Current size is %d", s.GetVolumeSizeLimit(), v.ContentSize())
 		}
diff --git a/weed/storage/volume_read_write.go b/weed/storage/volume_read_write.go
index 6899ebbc1..bd268c1a6 100644
--- a/weed/storage/volume_read_write.go
+++ b/weed/storage/volume_read_write.go
@@ -77,7 +77,7 @@ func (v *Volume) AppendBlob(b []byte) (offset int64, err error) {
 	return
 }
 
-func (v *Volume) writeNeedle(n *needle.Needle) (offset uint64, size uint32, err error) {
+func (v *Volume) writeNeedle(n *needle.Needle) (offset uint64, size uint32, isUnchanged bool, err error) {
 	glog.V(4).Infof("writing needle %s", needle.NewFileIdFromNeedle(v.Id, n).String())
 	if v.readOnly {
 		err = fmt.Errorf("%s is read-only", v.dataFile.Name())
@@ -87,7 +87,7 @@ func (v *Volume) writeNeedle(n *needle.Needle) (offset uint64, size uint32, err
 	defer v.dataFileAccessLock.Unlock()
 	if v.isFileUnchanged(n) {
 		size = n.DataSize
-		glog.V(4).Infof("needle is unchanged!")
+		isUnchanged = true
 		return
 	}
 
diff --git a/weed/storage/volume_vacuum_test.go b/weed/storage/volume_vacuum_test.go
index 5192d23b8..d038eeda3 100644
--- a/weed/storage/volume_vacuum_test.go
+++ b/weed/storage/volume_vacuum_test.go
@@ -124,7 +124,7 @@ func TestCompaction(t *testing.T) {
 }
 func doSomeWritesDeletes(i int, v *Volume, t *testing.T, infos []*needleInfo) {
 	n := newRandomNeedle(uint64(i))
-	_, size, err := v.writeNeedle(n)
+	_, size, _, err := v.writeNeedle(n)
 	if err != nil {
 		t.Fatalf("write file %d: %v", i, err)
 	}
diff --git a/weed/topology/store_replicate.go b/weed/topology/store_replicate.go
index fd19cbfba..d4076d548 100644
--- a/weed/topology/store_replicate.go
+++ b/weed/topology/store_replicate.go
@@ -20,19 +20,18 @@ import (
 
 func ReplicatedWrite(masterNode string, s *storage.Store,
 	volumeId needle.VolumeId, n *needle.Needle,
-	r *http.Request) (size uint32, errorStatus string) {
+	r *http.Request) (size uint32, isUnchanged bool, err error) {
 
 	//check JWT
 	jwt := security.GetJwt(r)
 
-	ret, err := s.Write(volumeId, n)
-	needToReplicate := !s.HasVolume(volumeId)
+	size, isUnchanged, err = s.Write(volumeId, n)
 	if err != nil {
-		errorStatus = "Failed to write to local disk (" + err.Error() + ")"
-		size = ret
+		err = fmt.Errorf("failed to write to local disk: %v", err)
 		return
 	}
 
+	needToReplicate := !s.HasVolume(volumeId)
 	needToReplicate = needToReplicate || s.GetVolume(volumeId).NeedToReplicate()
 	if !needToReplicate {
 		needToReplicate = s.GetVolume(volumeId).NeedToReplicate()
@@ -75,12 +74,11 @@ func ReplicatedWrite(masterNode string, s *storage.Store,
 					pairMap, jwt)
 				return err
 			}); err != nil {
-				ret = 0
-				errorStatus = fmt.Sprintf("Failed to write to replicas for volume %d: %v", volumeId, err)
+				size = 0
+				err = fmt.Errorf("failed to write to replicas for volume %d: %v", volumeId, err)
 			}
 		}
 	}
-	size = ret
 	return
 }