diff --git a/weed/filer2/filechunk_manifest.go b/weed/filer2/filechunk_manifest.go
index 92b114853..bab73c24a 100644
--- a/weed/filer2/filechunk_manifest.go
+++ b/weed/filer2/filechunk_manifest.go
@@ -13,6 +13,10 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/util"
 )
 
+const (
+	ManifestBatch = 10000
+)
+
 func HasChunkManifest(chunks []*filer_pb.FileChunk) bool {
 	for _, chunk := range chunks {
 		if chunk.IsChunkManifest {
@@ -51,10 +55,11 @@ func ResolveChunkManifest(lookupFileIdFn LookupFileIdFunctionType, chunks []*fil
 	return
 }
 
+// TODO fetch from cache for weed mount?
 func fetchChunk(lookupFileIdFn LookupFileIdFunctionType, fileId string, cipherKey []byte, isGzipped bool) ([]byte, error) {
 	urlString, err := lookupFileIdFn(fileId)
 	if err != nil {
-		glog.V(1).Infof("operation LookupFileId %s failed, err: %v", fileId, err)
+		glog.Errorf("operation LookupFileId %s failed, err: %v", fileId, err)
 		return nil, err
 	}
 	var buffer bytes.Buffer
@@ -69,8 +74,8 @@ func fetchChunk(lookupFileIdFn LookupFileIdFunctionType, fileId string, cipherKe
 	return buffer.Bytes(), nil
 }
 
-func MaybeManifestize(saveFunc SaveDataAsChunkFunctionType, dataChunks []*filer_pb.FileChunk) (chunks []*filer_pb.FileChunk, err error) {
-	return doMaybeManifestize(saveFunc, dataChunks, 10000, mergeIntoManifest)
+func MaybeManifestize(saveFunc SaveDataAsChunkFunctionType, inputChunks []*filer_pb.FileChunk) (chunks []*filer_pb.FileChunk, err error) {
+	return doMaybeManifestize(saveFunc, inputChunks, ManifestBatch, mergeIntoManifest)
 }
 
 func doMaybeManifestize(saveFunc SaveDataAsChunkFunctionType, inputChunks []*filer_pb.FileChunk, mergeFactor int, mergefn func(saveFunc SaveDataAsChunkFunctionType, dataChunks []*filer_pb.FileChunk) (manifestChunk *filer_pb.FileChunk, err error)) (chunks []*filer_pb.FileChunk, err error) {
@@ -84,15 +89,14 @@ func doMaybeManifestize(saveFunc SaveDataAsChunkFunctionType, inputChunks []*fil
 		}
 	}
 
-	manifestBatch := mergeFactor
 	remaining := len(dataChunks)
-	for i := 0; i+manifestBatch <= len(dataChunks); i += manifestBatch {
-		chunk, err := mergefn(saveFunc, dataChunks[i:i+manifestBatch])
+	for i := 0; i+mergeFactor <= len(dataChunks); i += mergeFactor {
+		chunk, err := mergefn(saveFunc, dataChunks[i:i+mergeFactor])
 		if err != nil {
 			return dataChunks, err
 		}
 		chunks = append(chunks, chunk)
-		remaining -= manifestBatch
+		remaining -= mergeFactor
 	}
 	// remaining
 	for i := len(dataChunks) - remaining; i < len(dataChunks); i++ {
@@ -112,8 +116,7 @@ func mergeIntoManifest(saveFunc SaveDataAsChunkFunctionType, dataChunks []*filer
 	}
 
 	minOffset, maxOffset := int64(math.MaxInt64), int64(math.MinInt64)
-	for k := 0; k < len(dataChunks); k++ {
-		chunk := dataChunks[k]
+	for _, chunk := range dataChunks {
 		if minOffset > int64(chunk.Offset) {
 			minOffset = chunk.Offset
 		}