diff --git a/weed/filer2/embedded/embedded_store.go b/weed/filer2/embedded/embedded_store.go
index f871f18e2..d0cfac3f9 100644
--- a/weed/filer2/embedded/embedded_store.go
+++ b/weed/filer2/embedded/embedded_store.go
@@ -26,7 +26,7 @@ func (filer *EmbeddedStore) AddDirectoryLink(directory *filer2.Entry, delta int3
 	return nil
 }
 
-func (filer *EmbeddedStore) AppendFileChunk(fullpath filer2.FullPath, fileChunks []*filer_pb.FileChunk) (err error) {
+func (filer *EmbeddedStore) SetFileChunks(fullpath filer2.FullPath, fileChunks []*filer_pb.FileChunk) (err error) {
 	return nil
 }
 
diff --git a/weed/filer2/filechunks.go b/weed/filer2/filechunks.go
index 88a2660cb..714bdab9c 100644
--- a/weed/filer2/filechunks.go
+++ b/weed/filer2/filechunks.go
@@ -19,12 +19,27 @@ func TotalSize(chunks []*filer_pb.FileChunk) (size uint64) {
 }
 
 func CompactFileChunks(chunks []*filer_pb.FileChunk) (compacted, garbage []*filer_pb.FileChunk) {
+
+	visibles := nonOverlappingVisibleIntervals(chunks)
+
+	fileIds := make(map[string]bool)
+	for _, interval := range visibles {
+		fileIds[interval.fileId] = true
+	}
+	for _, chunk := range chunks {
+		if found := fileIds[chunk.FileId]; found {
+			compacted = append(compacted, chunk)
+		} else {
+			garbage = append(garbage, chunk)
+		}
+	}
+
 	return
 }
 
 func logPrintf(name string, visibles []*visibleInterval) {
 
-	return
+	// return
 
 	log.Printf("%s len %d", name, len(visibles))
 	for _, v := range visibles {
@@ -52,7 +67,7 @@ func nonOverlappingVisibleIntervals(chunks []*filer_pb.FileChunk) (visibles []*v
 	var minStopInterval, upToDateInterval *visibleInterval
 	watermarkStart := chunks[0].Offset
 	for _, chunk := range chunks {
-		// log.Printf("checking chunk: [%d,%d)", chunk.Offset, chunk.Offset+int64(chunk.Size))
+		log.Printf("checking chunk: [%d,%d)", chunk.Offset, chunk.Offset+int64(chunk.Size))
 		logPrintf("parallelIntervals", parallelIntervals)
 		for len(parallelIntervals) > 0 && watermarkStart < chunk.Offset {
 			logPrintf("parallelIntervals loop 1", parallelIntervals)
@@ -72,12 +87,7 @@ func nonOverlappingVisibleIntervals(chunks []*filer_pb.FileChunk) (visibles []*v
 			var remaining []*visibleInterval
 			for _, interval := range parallelIntervals {
 				if interval.stop != watermarkStart {
-					remaining = append(remaining, newVisibleInterval(
-						interval.start,
-						interval.stop,
-						interval.fileId,
-						interval.modifiedTime,
-					))
+					remaining = append(remaining, interval)
 				}
 			}
 			parallelIntervals = remaining
@@ -108,12 +118,7 @@ func nonOverlappingVisibleIntervals(chunks []*filer_pb.FileChunk) (visibles []*v
 		var remaining []*visibleInterval
 		for _, interval := range parallelIntervals {
 			if interval.stop != watermarkStart {
-				remaining = append(remaining, newVisibleInterval(
-					interval.start,
-					interval.stop,
-					interval.fileId,
-					interval.modifiedTime,
-				))
+				remaining = append(remaining, interval)
 			}
 		}
 		parallelIntervals = remaining
@@ -122,11 +127,12 @@ func nonOverlappingVisibleIntervals(chunks []*filer_pb.FileChunk) (visibles []*v
 	logPrintf("intervals", intervals)
 
 	// merge connected intervals, now the intervals are non-intersecting
-	var lastInterval *visibleInterval
+	var lastIntervalIndex int
 	var prevIntervalIndex int
 	for i, interval := range intervals {
 		if i == 0 {
 			prevIntervalIndex = i
+			lastIntervalIndex = i
 			continue
 		}
 		if intervals[i-1].fileId != interval.fileId ||
@@ -139,18 +145,16 @@ func nonOverlappingVisibleIntervals(chunks []*filer_pb.FileChunk) (visibles []*v
 			))
 			prevIntervalIndex = i
 		}
-		lastInterval = intervals[i]
+		lastIntervalIndex = i
 		logPrintf("intervals loop 1 visibles", visibles)
 	}
 
-	if lastInterval != nil {
-		visibles = append(visibles, newVisibleInterval(
-			intervals[prevIntervalIndex].start,
-			lastInterval.stop,
-			intervals[prevIntervalIndex].fileId,
-			intervals[prevIntervalIndex].modifiedTime,
-		))
-	}
+	visibles = append(visibles, newVisibleInterval(
+		intervals[prevIntervalIndex].start,
+		intervals[lastIntervalIndex].stop,
+		intervals[prevIntervalIndex].fileId,
+		intervals[prevIntervalIndex].modifiedTime,
+	))
 
 	logPrintf("visibles", visibles)
 
diff --git a/weed/filer2/filechunks_test.go b/weed/filer2/filechunks_test.go
index a1614641a..b87b61d3b 100644
--- a/weed/filer2/filechunks_test.go
+++ b/weed/filer2/filechunks_test.go
@@ -7,6 +7,28 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 )
 
+func TestCompactFileChunks(t *testing.T) {
+	chunks := []*filer_pb.FileChunk{
+		{Offset:10, Size:100, FileId:"abc", Mtime:50},
+		{Offset:100, Size:100, FileId:"def", Mtime:100},
+		{Offset:200, Size:100, FileId:"ghi", Mtime:200},
+		{Offset:110, Size:200, FileId:"jkl", Mtime:300},
+	}
+
+	compacted, garbarge := CompactFileChunks(chunks)
+
+	log.Printf("Compacted: %+v", compacted)
+	log.Printf("Garbage  : %+v", garbarge)
+
+	if len(compacted) != 3 {
+		t.Fatalf("unexpected compacted: %d", len(compacted))
+	}
+	if len(garbarge) != 1 {
+		t.Fatalf("unexpected garbarge: %d", len(garbarge))
+	}
+
+}
+
 func TestIntervalMerging(t *testing.T) {
 
 	testcases := []struct {
@@ -84,6 +106,17 @@ func TestIntervalMerging(t *testing.T) {
 				{start: 200, stop: 220, fileId: "abc"},
 			},
 		},
+		// case 6: same updates
+		{
+			Chunks: []*filer_pb.FileChunk{
+				{Offset: 0, Size: 100, FileId: "abc", Mtime: 123},
+				{Offset: 0, Size: 100, FileId: "abc", Mtime: 123},
+				{Offset: 0, Size: 100, FileId: "abc", Mtime: 123},
+			},
+			Expected: []*visibleInterval{
+				{start: 0, stop: 100, fileId: "abc"},
+			},
+		},
 	}
 
 	for i, testcase := range testcases {
diff --git a/weed/filer2/filer.go b/weed/filer2/filer.go
index 2d5920cd8..fd27760bf 100644
--- a/weed/filer2/filer.go
+++ b/weed/filer2/filer.go
@@ -113,8 +113,8 @@ func (f *Filer) CreateEntry(entry *Entry) (error) {
 	return nil
 }
 
-func (f *Filer) AppendFileChunk(p FullPath, chunks []*filer_pb.FileChunk) (err error) {
-	return f.store.AppendFileChunk(p, chunks)
+func (f *Filer) SetFileChunks(p FullPath, chunks []*filer_pb.FileChunk) (err error) {
+	return f.store.SetFileChunks(p, chunks)
 }
 
 func (f *Filer) FindEntry(p FullPath) (found bool, entry *Entry, err error) {
diff --git a/weed/filer2/filer_structure.go b/weed/filer2/filer_structure.go
index 1d2da752d..51de09718 100644
--- a/weed/filer2/filer_structure.go
+++ b/weed/filer2/filer_structure.go
@@ -68,7 +68,7 @@ var ErrNotFound = errors.New("filer: no entry is found in filer store")
 
 type FilerStore interface {
 	InsertEntry(*Entry) (error)
-	AppendFileChunk(FullPath, []*filer_pb.FileChunk) (err error)
+	SetFileChunks(FullPath, []*filer_pb.FileChunk) (err error)
 	FindEntry(FullPath) (found bool, entry *Entry, err error)
 	DeleteEntry(FullPath) (fileEntry *Entry, err error)
 
diff --git a/weed/filer2/memdb/memdb_store.go b/weed/filer2/memdb/memdb_store.go
index 7e886f4ef..1e888cc45 100644
--- a/weed/filer2/memdb/memdb_store.go
+++ b/weed/filer2/memdb/memdb_store.go
@@ -33,14 +33,13 @@ func (filer *MemDbStore) InsertEntry(entry *filer2.Entry) (err error) {
 	return nil
 }
 
-func (filer *MemDbStore) AppendFileChunk(fullpath filer2.FullPath, fileChunks []*filer_pb.FileChunk) (err error) {
+func (filer *MemDbStore) SetFileChunks(fullpath filer2.FullPath, fileChunks []*filer_pb.FileChunk) (err error) {
 	found, entry, err := filer.FindEntry(fullpath)
 	if !found {
 		return fmt.Errorf("No such file: %s", fullpath)
 	}
-	entry.Chunks = append(entry.Chunks, fileChunks...)
+	entry.Chunks = fileChunks
 	entry.Mtime = time.Now()
-	println("appending to entry", entry.Name(), len(entry.Chunks))
 	filer.tree.ReplaceOrInsert(Entry{entry})
 	return nil
 }
diff --git a/weed/filesys/dir.go b/weed/filesys/dir.go
index 732912a99..50b37f883 100644
--- a/weed/filesys/dir.go
+++ b/weed/filesys/dir.go
@@ -169,7 +169,7 @@ func (dir *Dir) ReadDirAll(ctx context.Context) (ret []fuse.Dirent, err error) {
 			} else {
 				dirent := fuse.Dirent{Name: entry.Name, Type: fuse.DT_File}
 				ret = append(ret, dirent)
-				dir.wfs.listDirectoryEntriesCache.Set(dir.Path+"/"+entry.Name, entry.Attributes, 3*time.Second)
+				dir.wfs.listDirectoryEntriesCache.Set(dir.Path+"/"+entry.Name, entry.Attributes, 300*time.Millisecond)
 			}
 		}
 
diff --git a/weed/filesys/file.go b/weed/filesys/file.go
index 230ff272f..d4a9c8b05 100644
--- a/weed/filesys/file.go
+++ b/weed/filesys/file.go
@@ -13,6 +13,7 @@ import (
 	"time"
 	"bytes"
 	"github.com/chrislusf/seaweedfs/weed/operation"
+	"github.com/chrislusf/seaweedfs/weed/filer2"
 )
 
 var _ = fs.Node(&File{})
@@ -24,6 +25,7 @@ var _ = fs.HandleReadAller(&File{})
 var _ = fs.HandleFlusher(&File{})
 var _ = fs.HandleWriter(&File{})
 var _ = fs.HandleReleaser(&File{})
+var _ = fs.NodeSetattrer(&File{})
 
 type File struct {
 	Chunks []*filer_pb.FileChunk
@@ -74,9 +76,32 @@ func (file *File) Attr(context context.Context, attr *fuse.Attr) error {
 
 }
 
+func (file *File) xOpen(ctx context.Context, req *fuse.OpenRequest, resp *fuse.OpenResponse) (fs.Handle, error) {
+	fullPath := filepath.Join(file.dir.Path, file.Name)
+
+	fmt.Printf("Open %v %+v\n", fullPath, req)
+
+	return file, nil
+
+}
+
+func (file *File) Setattr(ctx context.Context, req *fuse.SetattrRequest, resp *fuse.SetattrResponse) error {
+	fullPath := filepath.Join(file.dir.Path, file.Name)
+
+	fmt.Printf("Setattr %v %+v\n", fullPath, req)
+	if req.Valid.Size() && req.Size == 0 {
+		fmt.Printf("truncate %v \n", fullPath)
+		file.Chunks = nil
+		resp.Attr.Size = 0
+	}
+
+	return nil
+
+}
+
 func (file *File) ReadAll(ctx context.Context) (content []byte, err error) {
 
-	// fmt.Printf("read all file %+v/%v\n", file.dir.Path, file.Name)
+	fmt.Printf("read all file %+v/%v\n", file.dir.Path, file.Name)
 
 	if len(file.Chunks) == 0 {
 		glog.V(0).Infof("empty file %v/%v", file.dir.Path, file.Name)
@@ -86,11 +111,14 @@ func (file *File) ReadAll(ctx context.Context) (content []byte, err error) {
 	err = file.wfs.withFilerClient(func(client filer_pb.SeaweedFilerClient) error {
 
 		// FIXME: need to either use Read() or implement differently
+		chunks, _ := filer2.CompactFileChunks(file.Chunks)
+		glog.V(1).Infof("read file %v/%v %d/%d chunks", file.dir.Path, file.Name, len(chunks), len(file.Chunks))
 		request := &filer_pb.GetFileContentRequest{
-			FileId: file.Chunks[0].FileId,
+			FileId: chunks[0].FileId,
 		}
 
-		glog.V(1).Infof("read file content: %v", request)
+		glog.V(1).Infof("read file content %d chunk %s [%d,%d): %v", len(chunks),
+			chunks[0].FileId, chunks[0].Offset, chunks[0].Offset+int64(chunks[0].Size), request)
 		resp, err := client.GetFileContent(ctx, request)
 		if err != nil {
 			return err
@@ -124,7 +152,7 @@ func (file *File) Flush(ctx context.Context, req *fuse.FlushRequest) error {
 
 	err := file.wfs.withFilerClient(func(client filer_pb.SeaweedFilerClient) error {
 
-		request := &filer_pb.AppendFileChunksRequest{
+		request := &filer_pb.SetFileChunksRequest{
 			Directory: file.dir.Path,
 			Entry: &filer_pb.Entry{
 				Name:   file.Name,
@@ -133,7 +161,7 @@ func (file *File) Flush(ctx context.Context, req *fuse.FlushRequest) error {
 		}
 
 		glog.V(1).Infof("append chunks: %v", request)
-		if _, err := client.AppendFileChunks(ctx, request); err != nil {
+		if _, err := client.SetFileChunks(ctx, request); err != nil {
 			return fmt.Errorf("create file: %v", err)
 		}
 
@@ -180,7 +208,7 @@ func (file *File) Write(ctx context.Context, req *fuse.WriteRequest, resp *fuse.
 		return fmt.Errorf("upload result: %v", uploadResult.Error)
 	}
 
-	glog.V(1).Infof("uploaded %s/%s to: %v", file.dir.Path, file.Name, fileUrl)
+	resp.Size = int(uploadResult.Size)
 
 	file.Chunks = append(file.Chunks, &filer_pb.FileChunk{
 		FileId: fileId,
@@ -189,7 +217,7 @@ func (file *File) Write(ctx context.Context, req *fuse.WriteRequest, resp *fuse.
 		Mtime:  time.Now().UnixNano(),
 	})
 
-	resp.Size = int(uploadResult.Size)
+	glog.V(1).Infof("uploaded %s/%s to: %v, [%d,%d)", file.dir.Path, file.Name, fileUrl, req.Offset, req.Offset+int64(resp.Size))
 
 	return nil
 }
diff --git a/weed/pb/filer.proto b/weed/pb/filer.proto
index 461a76a58..36b633899 100644
--- a/weed/pb/filer.proto
+++ b/weed/pb/filer.proto
@@ -21,7 +21,7 @@ service SeaweedFiler {
     rpc CreateEntry (CreateEntryRequest) returns (CreateEntryResponse) {
     }
 
-    rpc AppendFileChunks (AppendFileChunksRequest) returns (AppendFileChunksResponse) {
+    rpc SetFileChunks (SetFileChunksRequest) returns (SetFileChunksResponse) {
     }
 
     rpc DeleteEntry (DeleteEntryRequest) returns (DeleteEntryResponse) {
@@ -121,9 +121,9 @@ message AssignVolumeResponse {
     int32 count = 4;
 }
 
-message AppendFileChunksRequest {
+message SetFileChunksRequest {
     string directory = 1;
     Entry entry = 2;
 }
-message AppendFileChunksResponse {
+message SetFileChunksResponse {
 }
diff --git a/weed/pb/filer_pb/filer.pb.go b/weed/pb/filer_pb/filer.pb.go
index fc3bb65c6..6bcecb08c 100644
--- a/weed/pb/filer_pb/filer.pb.go
+++ b/weed/pb/filer_pb/filer.pb.go
@@ -26,8 +26,8 @@ It has these top-level messages:
 	DeleteEntryResponse
 	AssignVolumeRequest
 	AssignVolumeResponse
-	AppendFileChunksRequest
-	AppendFileChunksResponse
+	SetFileChunksRequest
+	SetFileChunksResponse
 */
 package filer_pb
 
@@ -475,37 +475,37 @@ func (m *AssignVolumeResponse) GetCount() int32 {
 	return 0
 }
 
-type AppendFileChunksRequest struct {
+type SetFileChunksRequest struct {
 	Directory string `protobuf:"bytes,1,opt,name=directory" json:"directory,omitempty"`
 	Entry     *Entry `protobuf:"bytes,2,opt,name=entry" json:"entry,omitempty"`
 }
 
-func (m *AppendFileChunksRequest) Reset()                    { *m = AppendFileChunksRequest{} }
-func (m *AppendFileChunksRequest) String() string            { return proto.CompactTextString(m) }
-func (*AppendFileChunksRequest) ProtoMessage()               {}
-func (*AppendFileChunksRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{17} }
+func (m *SetFileChunksRequest) Reset()                    { *m = SetFileChunksRequest{} }
+func (m *SetFileChunksRequest) String() string            { return proto.CompactTextString(m) }
+func (*SetFileChunksRequest) ProtoMessage()               {}
+func (*SetFileChunksRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{17} }
 
-func (m *AppendFileChunksRequest) GetDirectory() string {
+func (m *SetFileChunksRequest) GetDirectory() string {
 	if m != nil {
 		return m.Directory
 	}
 	return ""
 }
 
-func (m *AppendFileChunksRequest) GetEntry() *Entry {
+func (m *SetFileChunksRequest) GetEntry() *Entry {
 	if m != nil {
 		return m.Entry
 	}
 	return nil
 }
 
-type AppendFileChunksResponse struct {
+type SetFileChunksResponse struct {
 }
 
-func (m *AppendFileChunksResponse) Reset()                    { *m = AppendFileChunksResponse{} }
-func (m *AppendFileChunksResponse) String() string            { return proto.CompactTextString(m) }
-func (*AppendFileChunksResponse) ProtoMessage()               {}
-func (*AppendFileChunksResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{18} }
+func (m *SetFileChunksResponse) Reset()                    { *m = SetFileChunksResponse{} }
+func (m *SetFileChunksResponse) String() string            { return proto.CompactTextString(m) }
+func (*SetFileChunksResponse) ProtoMessage()               {}
+func (*SetFileChunksResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{18} }
 
 func init() {
 	proto.RegisterType((*LookupDirectoryEntryRequest)(nil), "filer_pb.LookupDirectoryEntryRequest")
@@ -525,8 +525,8 @@ func init() {
 	proto.RegisterType((*DeleteEntryResponse)(nil), "filer_pb.DeleteEntryResponse")
 	proto.RegisterType((*AssignVolumeRequest)(nil), "filer_pb.AssignVolumeRequest")
 	proto.RegisterType((*AssignVolumeResponse)(nil), "filer_pb.AssignVolumeResponse")
-	proto.RegisterType((*AppendFileChunksRequest)(nil), "filer_pb.AppendFileChunksRequest")
-	proto.RegisterType((*AppendFileChunksResponse)(nil), "filer_pb.AppendFileChunksResponse")
+	proto.RegisterType((*SetFileChunksRequest)(nil), "filer_pb.SetFileChunksRequest")
+	proto.RegisterType((*SetFileChunksResponse)(nil), "filer_pb.SetFileChunksResponse")
 }
 
 // Reference imports to suppress errors if they are not otherwise used.
@@ -545,7 +545,7 @@ type SeaweedFilerClient interface {
 	GetFileAttributes(ctx context.Context, in *GetFileAttributesRequest, opts ...grpc.CallOption) (*GetFileAttributesResponse, error)
 	GetFileContent(ctx context.Context, in *GetFileContentRequest, opts ...grpc.CallOption) (*GetFileContentResponse, error)
 	CreateEntry(ctx context.Context, in *CreateEntryRequest, opts ...grpc.CallOption) (*CreateEntryResponse, error)
-	AppendFileChunks(ctx context.Context, in *AppendFileChunksRequest, opts ...grpc.CallOption) (*AppendFileChunksResponse, error)
+	SetFileChunks(ctx context.Context, in *SetFileChunksRequest, opts ...grpc.CallOption) (*SetFileChunksResponse, error)
 	DeleteEntry(ctx context.Context, in *DeleteEntryRequest, opts ...grpc.CallOption) (*DeleteEntryResponse, error)
 	AssignVolume(ctx context.Context, in *AssignVolumeRequest, opts ...grpc.CallOption) (*AssignVolumeResponse, error)
 }
@@ -603,9 +603,9 @@ func (c *seaweedFilerClient) CreateEntry(ctx context.Context, in *CreateEntryReq
 	return out, nil
 }
 
-func (c *seaweedFilerClient) AppendFileChunks(ctx context.Context, in *AppendFileChunksRequest, opts ...grpc.CallOption) (*AppendFileChunksResponse, error) {
-	out := new(AppendFileChunksResponse)
-	err := grpc.Invoke(ctx, "/filer_pb.SeaweedFiler/AppendFileChunks", in, out, c.cc, opts...)
+func (c *seaweedFilerClient) SetFileChunks(ctx context.Context, in *SetFileChunksRequest, opts ...grpc.CallOption) (*SetFileChunksResponse, error) {
+	out := new(SetFileChunksResponse)
+	err := grpc.Invoke(ctx, "/filer_pb.SeaweedFiler/SetFileChunks", in, out, c.cc, opts...)
 	if err != nil {
 		return nil, err
 	}
@@ -638,7 +638,7 @@ type SeaweedFilerServer interface {
 	GetFileAttributes(context.Context, *GetFileAttributesRequest) (*GetFileAttributesResponse, error)
 	GetFileContent(context.Context, *GetFileContentRequest) (*GetFileContentResponse, error)
 	CreateEntry(context.Context, *CreateEntryRequest) (*CreateEntryResponse, error)
-	AppendFileChunks(context.Context, *AppendFileChunksRequest) (*AppendFileChunksResponse, error)
+	SetFileChunks(context.Context, *SetFileChunksRequest) (*SetFileChunksResponse, error)
 	DeleteEntry(context.Context, *DeleteEntryRequest) (*DeleteEntryResponse, error)
 	AssignVolume(context.Context, *AssignVolumeRequest) (*AssignVolumeResponse, error)
 }
@@ -737,20 +737,20 @@ func _SeaweedFiler_CreateEntry_Handler(srv interface{}, ctx context.Context, dec
 	return interceptor(ctx, in, info, handler)
 }
 
-func _SeaweedFiler_AppendFileChunks_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(AppendFileChunksRequest)
+func _SeaweedFiler_SetFileChunks_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(SetFileChunksRequest)
 	if err := dec(in); err != nil {
 		return nil, err
 	}
 	if interceptor == nil {
-		return srv.(SeaweedFilerServer).AppendFileChunks(ctx, in)
+		return srv.(SeaweedFilerServer).SetFileChunks(ctx, in)
 	}
 	info := &grpc.UnaryServerInfo{
 		Server:     srv,
-		FullMethod: "/filer_pb.SeaweedFiler/AppendFileChunks",
+		FullMethod: "/filer_pb.SeaweedFiler/SetFileChunks",
 	}
 	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(SeaweedFilerServer).AppendFileChunks(ctx, req.(*AppendFileChunksRequest))
+		return srv.(SeaweedFilerServer).SetFileChunks(ctx, req.(*SetFileChunksRequest))
 	}
 	return interceptor(ctx, in, info, handler)
 }
@@ -816,8 +816,8 @@ var _SeaweedFiler_serviceDesc = grpc.ServiceDesc{
 			Handler:    _SeaweedFiler_CreateEntry_Handler,
 		},
 		{
-			MethodName: "AppendFileChunks",
-			Handler:    _SeaweedFiler_AppendFileChunks_Handler,
+			MethodName: "SetFileChunks",
+			Handler:    _SeaweedFiler_SetFileChunks_Handler,
 		},
 		{
 			MethodName: "DeleteEntry",
@@ -835,53 +835,53 @@ var _SeaweedFiler_serviceDesc = grpc.ServiceDesc{
 func init() { proto.RegisterFile("filer.proto", fileDescriptor0) }
 
 var fileDescriptor0 = []byte{
-	// 767 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0xac, 0x56, 0x6d, 0x4f, 0xdb, 0x48,
-	0x10, 0xc6, 0x38, 0x09, 0x64, 0x12, 0x38, 0x6e, 0x13, 0xc0, 0x17, 0x5e, 0x2e, 0xec, 0x89, 0x13,
-	0xa7, 0x93, 0xd0, 0x29, 0xf7, 0xa5, 0x1f, 0x8b, 0x80, 0x56, 0x95, 0xa8, 0x90, 0x8c, 0xa8, 0x54,
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 }
diff --git a/weed/server/filer_grpc_server.go b/weed/server/filer_grpc_server.go
index 6cc5021d6..a279b7dd7 100644
--- a/weed/server/filer_grpc_server.go
+++ b/weed/server/filer_grpc_server.go
@@ -116,13 +116,34 @@ func (fs *FilerServer) CreateEntry(ctx context.Context, req *filer_pb.CreateEntr
 	return &filer_pb.CreateEntryResponse{}, err
 }
 
-func (fs *FilerServer) AppendFileChunks(ctx context.Context, req *filer_pb.AppendFileChunksRequest) (*filer_pb.AppendFileChunksResponse, error) {
-	err := fs.filer.AppendFileChunk(
-		filer2.FullPath(filepath.Join(req.Directory, req.Entry.Name)),
-		req.Entry.Chunks,
+func (fs *FilerServer) SetFileChunks(ctx context.Context, req *filer_pb.SetFileChunksRequest) (*filer_pb.SetFileChunksResponse, error) {
+
+	fullpath := filepath.Join(req.Directory, req.Entry.Name)
+	found, entry, err := fs.filer.FindEntry(filer2.FullPath(fullpath))
+	if err != nil {
+		return &filer_pb.SetFileChunksResponse{}, err
+	}
+	if !found {
+		return &filer_pb.SetFileChunksResponse{}, fmt.Errorf("file not found: %s", fullpath)
+	}
+
+	chunks := append(entry.Chunks, req.Entry.Chunks...)
+
+	chunks, garbages := filer2.CompactFileChunks(chunks)
+
+	err = fs.filer.SetFileChunks(
+		filer2.FullPath(fullpath),
+		chunks,
 	)
 
-	return &filer_pb.AppendFileChunksResponse{}, err
+	if err == nil {
+		for _, garbage := range garbages {
+			glog.V(0).Infof("deleting %s old chunk: %v, [%d, %d)", fullpath, garbage.FileId, garbage.Offset, garbage.Offset+int64(garbage.Size))
+			operation.DeleteFile(fs.master, garbage.FileId, fs.jwt(garbage.FileId))
+		}
+	}
+
+	return &filer_pb.SetFileChunksResponse{}, err
 }
 
 func (fs *FilerServer) DeleteEntry(ctx context.Context, req *filer_pb.DeleteEntryRequest) (resp *filer_pb.DeleteEntryResponse, err error) {