diff --git a/unmaintained/diff_volume_servers/diff_volume_servers.go b/unmaintained/diff_volume_servers/diff_volume_servers.go
index 0188d18d4..815eeae54 100644
--- a/unmaintained/diff_volume_servers/diff_volume_servers.go
+++ b/unmaintained/diff_volume_servers/diff_volume_servers.go
@@ -6,6 +6,10 @@ import (
 	"errors"
 	"flag"
 	"fmt"
+	"io"
+	"math"
+	"os"
+
 	"github.com/chrislusf/seaweedfs/weed/glog"
 	"github.com/chrislusf/seaweedfs/weed/operation"
 	"github.com/chrislusf/seaweedfs/weed/pb"
@@ -16,9 +20,6 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/storage/types"
 	"github.com/chrislusf/seaweedfs/weed/util"
 	"google.golang.org/grpc"
-	"io"
-	"math"
-	"os"
 )
 
 var (
@@ -155,7 +156,7 @@ func getVolumeFiles(v uint32, addr pb.ServerAddress) (map[types.NeedleId]needleS
 
 	var maxOffset int64
 	files := map[types.NeedleId]needleState{}
-	err = idx.WalkIndexFile(idxFile, func(key types.NeedleId, offset types.Offset, size types.Size) error {
+	err = idx.WalkIndexFile(idxFile, 0, func(key types.NeedleId, offset types.Offset, size types.Size) error {
 		if offset.IsZero() || size.IsDeleted() {
 			files[key] = needleState{
 				state: stateDeleted,
diff --git a/unmaintained/see_idx/see_idx.go b/unmaintained/see_idx/see_idx.go
index 22c659351..616263b1c 100644
--- a/unmaintained/see_idx/see_idx.go
+++ b/unmaintained/see_idx/see_idx.go
@@ -3,11 +3,12 @@ package main
 import (
 	"flag"
 	"fmt"
-	"github.com/chrislusf/seaweedfs/weed/util"
 	"os"
 	"path"
 	"strconv"
 
+	"github.com/chrislusf/seaweedfs/weed/util"
+
 	"github.com/chrislusf/seaweedfs/weed/glog"
 	"github.com/chrislusf/seaweedfs/weed/storage/idx"
 	"github.com/chrislusf/seaweedfs/weed/storage/types"
@@ -36,7 +37,7 @@ func main() {
 	}
 	defer indexFile.Close()
 
-	idx.WalkIndexFile(indexFile, func(key types.NeedleId, offset types.Offset, size types.Size) error {
+	idx.WalkIndexFile(indexFile, 0, func(key types.NeedleId, offset types.Offset, size types.Size) error {
 		fmt.Printf("key:%v offset:%v size:%v(%v)\n", key, offset, size, util.BytesToHumanReadable(uint64(size)))
 		return nil
 	})
diff --git a/weed/storage/erasure_coding/ec_encoder.go b/weed/storage/erasure_coding/ec_encoder.go
index 157149865..ea331ca39 100644
--- a/weed/storage/erasure_coding/ec_encoder.go
+++ b/weed/storage/erasure_coding/ec_encoder.go
@@ -294,7 +294,7 @@ func readNeedleMap(baseFileName string) (*needle_map.MemDb, error) {
 	defer indexFile.Close()
 
 	cm := needle_map.NewMemDb()
-	err = idx.WalkIndexFile(indexFile, func(key types.NeedleId, offset types.Offset, size types.Size) error {
+	err = idx.WalkIndexFile(indexFile, 0, func(key types.NeedleId, offset types.Offset, size types.Size) error {
 		if !offset.IsZero() && size != types.TombstoneFileSize {
 			cm.Set(key, offset, size)
 		} else {
diff --git a/weed/storage/idx/walk.go b/weed/storage/idx/walk.go
index 5215d3c4f..70d3855ea 100644
--- a/weed/storage/idx/walk.go
+++ b/weed/storage/idx/walk.go
@@ -9,8 +9,8 @@ import (
 
 // walks through the index file, calls fn function with each key, offset, size
 // stops with the error returned by the fn function
-func WalkIndexFile(r io.ReaderAt, fn func(key types.NeedleId, offset types.Offset, size types.Size) error) error {
-	var readerOffset int64
+func WalkIndexFile(r io.ReaderAt, startFrom uint64, fn func(key types.NeedleId, offset types.Offset, size types.Size) error) error {
+	readerOffset := int64(startFrom * types.NeedleMapEntrySize)
 	bytes := make([]byte, types.NeedleMapEntrySize*RowsToRead)
 	count, e := r.ReadAt(bytes, readerOffset)
 	if count == 0 && e == io.EOF {
diff --git a/weed/storage/needle_map/memdb.go b/weed/storage/needle_map/memdb.go
index ba1fd3d1e..a362a85ae 100644
--- a/weed/storage/needle_map/memdb.go
+++ b/weed/storage/needle_map/memdb.go
@@ -111,7 +111,7 @@ func (cm *MemDb) LoadFromIdx(idxName string) (ret error) {
 
 func (cm *MemDb) LoadFromReaderAt(readerAt io.ReaderAt) (ret error) {
 
-	return idx.WalkIndexFile(readerAt, func(key NeedleId, offset Offset, size Size) error {
+	return idx.WalkIndexFile(readerAt, 0, func(key NeedleId, offset Offset, size Size) error {
 		if offset.IsZero() || size.IsDeleted() {
 			return cm.Delete(key)
 		}
diff --git a/weed/storage/needle_map_leveldb.go b/weed/storage/needle_map_leveldb.go
index 31c86d124..a1934b8f1 100644
--- a/weed/storage/needle_map_leveldb.go
+++ b/weed/storage/needle_map_leveldb.go
@@ -9,6 +9,8 @@ import (
 	"github.com/syndtr/goleveldb/leveldb/opt"
 
 	"github.com/chrislusf/seaweedfs/weed/storage/idx"
+	"github.com/chrislusf/seaweedfs/weed/storage/types"
+	"github.com/chrislusf/seaweedfs/weed/util"
 
 	"github.com/syndtr/goleveldb/leveldb"
 
@@ -17,10 +19,16 @@ import (
 	. "github.com/chrislusf/seaweedfs/weed/storage/types"
 )
 
+//mark it every watermarkBatchSize operations
+const watermarkBatchSize = 10000
+
+var watermarkKey = []byte("idx_entry_watermark")
+
 type LevelDbNeedleMap struct {
 	baseNeedleMapper
-	dbFileName string
-	db         *leveldb.DB
+	dbFileName  string
+	db          *leveldb.DB
+	recordCount uint64
 }
 
 func NewLevelDbNeedleMap(dbFileName string, indexFile *os.File, opts *opt.Options) (m *LevelDbNeedleMap, err error) {
@@ -46,7 +54,14 @@ func NewLevelDbNeedleMap(dbFileName string, indexFile *os.File, opts *opt.Option
 			return
 		}
 	}
-	glog.V(1).Infof("Loading %s...", indexFile.Name())
+	glog.V(0).Infof("Loading %s... , watermark: %d", dbFileName, getWatermark(m.db))
+	m.recordCount = uint64(m.indexFileOffset / types.NeedleMapEntrySize)
+	watermark := (m.recordCount / watermarkBatchSize) * watermarkBatchSize
+	err = setWatermark(m.db, watermark)
+	if err != nil {
+		glog.Fatalf("set watermark for %s error: %s\n", dbFileName, err)
+		return
+	}
 	mm, indexLoadError := newNeedleMapMetricFromIndexFile(indexFile)
 	if indexLoadError != nil {
 		return nil, indexLoadError
@@ -78,9 +93,20 @@ func generateLevelDbFile(dbFileName string, indexFile *os.File) error {
 		return err
 	}
 	defer db.Close()
-	return idx.WalkIndexFile(indexFile, func(key NeedleId, offset Offset, size Size) error {
+
+	watermark := getWatermark(db)
+	if stat, err := indexFile.Stat(); err != nil {
+		glog.Fatalf("stat file %s: %v", indexFile.Name(), err)
+		return err
+	} else {
+		if watermark*types.NeedleMapEntrySize > uint64(stat.Size()) {
+			glog.Warningf("wrong watermark %d for filesize %d", watermark, stat.Size())
+		}
+		glog.V(0).Infof("generateLevelDbFile %s, watermark %d, num of entries:%d", dbFileName, watermark, (uint64(stat.Size())-watermark*types.NeedleMapEntrySize)/types.NeedleMapEntrySize)
+	}
+	return idx.WalkIndexFile(indexFile, watermark, func(key NeedleId, offset Offset, size Size) error {
 		if !offset.IsZero() && size.IsValid() {
-			levelDbWrite(db, key, offset, size)
+			levelDbWrite(db, key, offset, size, false, 0)
 		} else {
 			levelDbDelete(db, key)
 		}
@@ -102,6 +128,7 @@ func (m *LevelDbNeedleMap) Get(key NeedleId) (element *needle_map.NeedleValue, o
 
 func (m *LevelDbNeedleMap) Put(key NeedleId, offset Offset, size Size) error {
 	var oldSize Size
+	var watermark uint64
 	if oldNeedle, ok := m.Get(key); ok {
 		oldSize = oldNeedle.Size
 	}
@@ -110,16 +137,54 @@ func (m *LevelDbNeedleMap) Put(key NeedleId, offset Offset, size Size) error {
 	if err := m.appendToIndexFile(key, offset, size); err != nil {
 		return fmt.Errorf("cannot write to indexfile %s: %v", m.indexFile.Name(), err)
 	}
-	return levelDbWrite(m.db, key, offset, size)
+	m.recordCount++
+	if m.recordCount%watermarkBatchSize != 0 {
+		watermark = 0
+	} else {
+		watermark = (m.recordCount / watermarkBatchSize) * watermarkBatchSize
+		glog.V(1).Infof("put cnt:%d for %s,watermark: %d", m.recordCount, m.dbFileName, watermark)
+	}
+	return levelDbWrite(m.db, key, offset, size, watermark == 0, watermark)
 }
 
-func levelDbWrite(db *leveldb.DB, key NeedleId, offset Offset, size Size) error {
+func getWatermark(db *leveldb.DB) uint64 {
+	data, err := db.Get(watermarkKey, nil)
+	if err != nil || len(data) != 8 {
+		glog.Warningf("get watermark from db error: %v, %d", err, len(data))
+		/*
+			if !strings.Contains(strings.ToLower(err.Error()), "not found") {
+				err = setWatermark(db, 0)
+				if err != nil {
+					glog.Errorf("failed to set watermark: %v", err)
+				}
+			}
+		*/
+		return 0
+	}
+	return util.BytesToUint64(data)
+}
+
+func setWatermark(db *leveldb.DB, watermark uint64) error {
+	glog.V(1).Infof("set watermark %d", watermark)
+	var wmBytes = make([]byte, 8)
+	util.Uint64toBytes(wmBytes, watermark)
+	if err := db.Put(watermarkKey, wmBytes, nil); err != nil {
+		return fmt.Errorf("failed to setWatermark: %v", err)
+	}
+	return nil
+}
+
+func levelDbWrite(db *leveldb.DB, key NeedleId, offset Offset, size Size, updateWatermark bool, watermark uint64) error {
 
 	bytes := needle_map.ToBytes(key, offset, size)
 
 	if err := db.Put(bytes[0:NeedleIdSize], bytes[NeedleIdSize:NeedleIdSize+OffsetSize+SizeSize], nil); err != nil {
 		return fmt.Errorf("failed to write leveldb: %v", err)
 	}
+	// set watermark
+	if updateWatermark {
+		return setWatermark(db, watermark)
+	}
 	return nil
 }
 func levelDbDelete(db *leveldb.DB, key NeedleId) error {
@@ -129,6 +194,7 @@ func levelDbDelete(db *leveldb.DB, key NeedleId) error {
 }
 
 func (m *LevelDbNeedleMap) Delete(key NeedleId, offset Offset) error {
+	var watermark uint64
 	oldNeedle, found := m.Get(key)
 	if !found || oldNeedle.Size.IsDeleted() {
 		return nil
@@ -139,8 +205,13 @@ func (m *LevelDbNeedleMap) Delete(key NeedleId, offset Offset) error {
 	if err := m.appendToIndexFile(key, offset, TombstoneFileSize); err != nil {
 		return err
 	}
-
-	return levelDbWrite(m.db, key, oldNeedle.Offset, -oldNeedle.Size)
+	m.recordCount++
+	if m.recordCount%watermarkBatchSize != 0 {
+		watermark = 0
+	} else {
+		watermark = (m.recordCount / watermarkBatchSize) * watermarkBatchSize
+	}
+	return levelDbWrite(m.db, key, oldNeedle.Offset, -oldNeedle.Size, watermark == 0, watermark)
 }
 
 func (m *LevelDbNeedleMap) Close() {
diff --git a/weed/storage/needle_map_memory.go b/weed/storage/needle_map_memory.go
index 1b58708c6..4c7909dbd 100644
--- a/weed/storage/needle_map_memory.go
+++ b/weed/storage/needle_map_memory.go
@@ -33,7 +33,7 @@ func LoadCompactNeedleMap(file *os.File) (*NeedleMap, error) {
 }
 
 func doLoading(file *os.File, nm *NeedleMap) (*NeedleMap, error) {
-	e := idx.WalkIndexFile(file, func(key NeedleId, offset Offset, size Size) error {
+	e := idx.WalkIndexFile(file, 0, func(key NeedleId, offset Offset, size Size) error {
 		nm.MaybeSetMaxFileKey(key)
 		if !offset.IsZero() && size.IsValid() {
 			nm.FileCounter++