diff --git a/weed/storage/needle_map_sorted_file.go b/weed/storage/needle_map_sorted_file.go
index 83290796f..e6f9258f3 100644
--- a/weed/storage/needle_map_sorted_file.go
+++ b/weed/storage/needle_map_sorted_file.go
@@ -19,15 +19,15 @@ type SortedFileNeedleMap struct {
 func NewSortedFileNeedleMap(baseFileName string, indexFile *os.File) (m *SortedFileNeedleMap, err error) {
 	m = &SortedFileNeedleMap{baseFileName: baseFileName}
 	m.indexFile = indexFile
-	fileName := baseFileName + ".sdb"
+	fileName := baseFileName + ".sdx"
 	if !isSortedFileFresh(fileName, indexFile) {
 		glog.V(0).Infof("Start to Generate %s from %s", fileName, indexFile.Name())
-		erasure_coding.WriteSortedFileFromIdx(baseFileName, ".sdb")
+		erasure_coding.WriteSortedFileFromIdx(baseFileName, ".sdx")
 		glog.V(0).Infof("Finished Generating %s from %s", fileName, indexFile.Name())
 	}
 	glog.V(1).Infof("Opening %s...", fileName)
 
-	if m.dbFile, err = os.Open(baseFileName + ".sdb"); err != nil {
+	if m.dbFile, err = os.Open(baseFileName + ".sdx"); err != nil {
 		return
 	}
 	dbStat, _ := m.dbFile.Stat()
@@ -101,5 +101,5 @@ func (m *SortedFileNeedleMap) Close() {
 func (m *SortedFileNeedleMap) Destroy() error {
 	m.Close()
 	os.Remove(m.indexFile.Name())
-	return os.Remove(m.baseFileName + ".sdb")
+	return os.Remove(m.baseFileName + ".sdx")
 }
diff --git a/weed/storage/volume_loading.go b/weed/storage/volume_loading.go
index eb177e850..d87a58302 100644
--- a/weed/storage/volume_loading.go
+++ b/weed/storage/volume_loading.go
@@ -92,7 +92,7 @@ func (v *Volume) load(alsoLoadIndex bool, createDatIfMissing bool, needleMapKind
 
 		if v.noWriteOrDelete || v.noWriteCanDelete {
 			if v.nm, err = NewSortedFileNeedleMap(fileName, indexFile); err != nil {
-				glog.V(0).Infof("loading sorted db %s error: %v", fileName+".sdb", err)
+				glog.V(0).Infof("loading sorted db %s error: %v", fileName+".sdx", err)
 			}
 		} else {
 			switch needleMapKind {
diff --git a/weed/storage/volume_read_write.go b/weed/storage/volume_read_write.go
index a08e64077..7fe913869 100644
--- a/weed/storage/volume_read_write.go
+++ b/weed/storage/volume_read_write.go
@@ -50,7 +50,7 @@ func (v *Volume) Destroy() (err error) {
 	os.Remove(v.FileName() + ".dat")
 	os.Remove(v.FileName() + ".idx")
 	os.Remove(v.FileName() + ".tier")
-	os.Remove(v.FileName() + ".sdb")
+	os.Remove(v.FileName() + ".sdx")
 	os.Remove(v.FileName() + ".cpd")
 	os.Remove(v.FileName() + ".cpx")
 	os.RemoveAll(v.FileName() + ".ldb")