diff --git a/weed/filer2/filechunks.go b/weed/filer2/filechunks.go
index 257aba548..88a2660cb 100644
--- a/weed/filer2/filechunks.go
+++ b/weed/filer2/filechunks.go
@@ -1,10 +1,11 @@
 package filer2
 
 import (
-	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 	"sort"
 	"log"
 	"math"
+
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 )
 
 func TotalSize(chunks []*filer_pb.FileChunk) (size uint64) {
@@ -21,125 +22,10 @@ func CompactFileChunks(chunks []*filer_pb.FileChunk) (compacted, garbage []*file
 	return
 }
 
-func mergeToVisibleIntervals(visibles []*visibleInterval, chunk *filer_pb.FileChunk) (merged []*visibleInterval) {
-	if len(visibles) == 0 {
-		return []*visibleInterval{newVisibleInterval(chunk.Offset, chunk.Offset+int64(chunk.Size), chunk.FileId, chunk.Mtime)}
-	}
-
-	log.Printf("merge chunk %+v => %d", chunk, len(visibles))
-	for _, v := range visibles {
-		log.Printf("=> %+v", v)
-	}
-
-	var nonOverlappingStop int
-
-	// find merge candidates
-	var mergeCandidates []int
-	for t := len(visibles) - 1; t >= 0; t-- {
-		if visibles[t].stop > chunk.Offset {
-			mergeCandidates = append(mergeCandidates, t)
-		} else {
-			nonOverlappingStop = t
-			break
-		}
-	}
-	log.Printf("merged candidates: %+v, starting from %d", mergeCandidates, nonOverlappingStop)
-
-	if len(mergeCandidates) == 0 {
-		merged = append(visibles, newVisibleInterval(
-			chunk.Offset,
-			chunk.Offset+int64(chunk.Size),
-			chunk.FileId,
-			chunk.Mtime,
-		))
-		return
-	}
-
-	// reverse merge candidates
-	i, j := 0, len(mergeCandidates)-1
-	for i < j {
-		mergeCandidates[i], mergeCandidates[j] = mergeCandidates[j], mergeCandidates[i]
-		i++
-		j--
-	}
-	log.Printf("reversed merged candidates: %+v", mergeCandidates)
-
-	// add chunk into a possibly connected intervals
-	var overlappingIntevals []*visibleInterval
-	for i = 0; i < len(mergeCandidates); i++ {
-		interval := visibles[mergeCandidates[i]]
-		if interval.modifiedTime >= chunk.Mtime {
-			log.Printf("overlappingIntevals add existing interval: [%d,%d)", interval.start, interval.stop)
-			overlappingIntevals = append(overlappingIntevals, interval)
-		} else {
-			start := max(interval.start, chunk.Offset)
-			stop := min(interval.stop, chunk.Offset+int64(chunk.Size))
-			if interval.start <= chunk.Offset {
-				if interval.start < start {
-					log.Printf("overlappingIntevals add 1: [%d,%d)", interval.start, start)
-					overlappingIntevals = append(overlappingIntevals, newVisibleInterval(
-						interval.start,
-						start,
-						interval.fileId,
-						interval.modifiedTime,
-					))
-				}
-				log.Printf("overlappingIntevals add 2: [%d,%d)", start, stop)
-				overlappingIntevals = append(overlappingIntevals, newVisibleInterval(
-					start,
-					stop,
-					chunk.FileId,
-					chunk.Mtime,
-				))
-				if interval.stop < stop {
-					log.Printf("overlappingIntevals add 3: [%d,%d)", interval.stop, stop)
-					overlappingIntevals = append(overlappingIntevals, newVisibleInterval(
-						interval.stop,
-						stop,
-						interval.fileId,
-						interval.modifiedTime,
-					))
-				}
-			}
-		}
-	}
-	logPrintf("overlappingIntevals", overlappingIntevals)
-
-	// merge connected intervals
-	merged = visibles[:nonOverlappingStop]
-	var lastInterval *visibleInterval
-	var prevIntervalIndex int
-	for i, interval := range overlappingIntevals {
-		if i == 0 {
-			prevIntervalIndex = i
-			continue
-		}
-		if overlappingIntevals[prevIntervalIndex].fileId != interval.fileId {
-			merged = append(merged, newVisibleInterval(
-				overlappingIntevals[prevIntervalIndex].start,
-				interval.start,
-				overlappingIntevals[prevIntervalIndex].fileId,
-				overlappingIntevals[prevIntervalIndex].modifiedTime,
-			))
-			prevIntervalIndex = i
-		}
-	}
-
-	if lastInterval != nil {
-		merged = append(merged, newVisibleInterval(
-			overlappingIntevals[prevIntervalIndex].start,
-			lastInterval.start,
-			overlappingIntevals[prevIntervalIndex].fileId,
-			overlappingIntevals[prevIntervalIndex].modifiedTime,
-		))
-	}
-
-	logPrintf("merged", merged)
+func logPrintf(name string, visibles []*visibleInterval) {
 
 	return
-}
 
-func logPrintf(name string, visibles []*visibleInterval) {
 	log.Printf("%s len %d", name, len(visibles))
 	for _, v := range visibles {
 		log.Printf("%s:  => %+v", name, v)
@@ -166,7 +52,7 @@ 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)
@@ -291,25 +177,6 @@ func findMinStopInterval(intervals []*visibleInterval) (minStopInterval, upToDat
 	return
 }
 
-func nonOverlappingVisibleIntervals0(chunks []*filer_pb.FileChunk) (visibles []*visibleInterval) {
-
-	sort.Slice(chunks, func(i, j int) bool {
-		if chunks[i].Offset < chunks[j].Offset {
-			return true
-		}
-		if chunks[i].Offset == chunks[j].Offset {
-			return chunks[i].Mtime < chunks[j].Mtime
-		}
-		return false
-	})
-
-	for _, c := range chunks {
-		visibles = mergeToVisibleIntervals(visibles, c)
-	}
-
-	return
-}
-
 // find non-overlapping visible intervals
 // visible interval map to one file chunk
 
@@ -324,28 +191,6 @@ func newVisibleInterval(start, stop int64, fileId string, modifiedTime int64) *v
 	return &visibleInterval{start: start, stop: stop, fileId: fileId, modifiedTime: modifiedTime}
 }
 
-type stackOfChunkIds struct {
-	ids []int
-}
-
-func (s *stackOfChunkIds) isEmpty() bool {
-	return len(s.ids) == 0
-}
-
-func (s *stackOfChunkIds) pop() int {
-	t := s.ids[len(s.ids)-1]
-	s.ids = s.ids[:len(s.ids)-1]
-	return t
-}
-
-func (s *stackOfChunkIds) push(x int) {
-	s.ids = append(s.ids, x)
-}
-
-func (s *stackOfChunkIds) peek() int {
-	return s.ids[len(s.ids)-1]
-}
-
 func min(x, y int64) int64 {
 	if x <= y {
 		return x
diff --git a/weed/filer2/filechunks_test.go b/weed/filer2/filechunks_test.go
index e5cb8810f..a1614641a 100644
--- a/weed/filer2/filechunks_test.go
+++ b/weed/filer2/filechunks_test.go
@@ -2,8 +2,9 @@ package filer2
 
 import (
 	"testing"
-	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 	"log"
+
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 )
 
 func TestIntervalMerging(t *testing.T) {