diff --git a/weed/command/filer_sync.go b/weed/command/filer_sync.go
index 33dcf4073..b1e32b65e 100644
--- a/weed/command/filer_sync.go
+++ b/weed/command/filer_sync.go
@@ -47,6 +47,8 @@ type SyncOptions struct {
 	metricsHttpIp   *string
 	metricsHttpPort *int
 	concurrency     *int
+	aDoDeleteFiles  *bool
+	bDoDeleteFiles  *bool
 	clientId        int32
 	clientEpoch     int32
 }
@@ -90,6 +92,8 @@ func init() {
 	syncMemProfile = cmdFilerSynchronize.Flag.String("memprofile", "", "memory profile output file")
 	syncOptions.metricsHttpIp = cmdFilerSynchronize.Flag.String("metricsIp", "", "metrics listen ip")
 	syncOptions.metricsHttpPort = cmdFilerSynchronize.Flag.Int("metricsPort", 0, "metrics listen port")
+	syncOptions.aDoDeleteFiles = cmdFilerSynchronize.Flag.Bool("a.doDeleteFiles", true, "delete and update files when synchronizing on filer A")
+	syncOptions.bDoDeleteFiles = cmdFilerSynchronize.Flag.Bool("b.doDeleteFiles", true, "delete and update files when synchronizing on filer B")
 	syncOptions.clientId = util.RandomInt32()
 }
 
@@ -164,6 +168,7 @@ func runFilerSynchronize(cmd *Command, args []string) bool {
 				*syncOptions.bDiskType,
 				*syncOptions.bDebug,
 				*syncOptions.concurrency,
+				*syncOptions.bDoDeleteFiles,
 				aFilerSignature,
 				bFilerSignature)
 			if err != nil {
@@ -201,6 +206,7 @@ func runFilerSynchronize(cmd *Command, args []string) bool {
 					*syncOptions.aDiskType,
 					*syncOptions.aDebug,
 					*syncOptions.concurrency,
+					*syncOptions.aDoDeleteFiles,
 					bFilerSignature,
 					aFilerSignature)
 				if err != nil {
@@ -233,7 +239,7 @@ func initOffsetFromTsMs(grpcDialOption grpc.DialOption, targetFiler pb.ServerAdd
 }
 
 func doSubscribeFilerMetaChanges(clientId int32, clientEpoch int32, grpcDialOption grpc.DialOption, sourceFiler pb.ServerAddress, sourcePath string, sourceExcludePaths []string, sourceReadChunkFromFiler bool, targetFiler pb.ServerAddress, targetPath string,
-	replicationStr, collection string, ttlSec int, sinkWriteChunkByFiler bool, diskType string, debug bool, concurrency int, sourceFilerSignature int32, targetFilerSignature int32) error {
+	replicationStr, collection string, ttlSec int, sinkWriteChunkByFiler bool, diskType string, debug bool, concurrency int, doDeleteFiles bool, sourceFilerSignature int32, targetFilerSignature int32) error {
 
 	// if first time, start from now
 	// if has previously synced, resume from that point of time
@@ -251,7 +257,7 @@ func doSubscribeFilerMetaChanges(clientId int32, clientEpoch int32, grpcDialOpti
 	filerSink.DoInitialize(targetFiler.ToHttpAddress(), targetFiler.ToGrpcAddress(), targetPath, replicationStr, collection, ttlSec, diskType, grpcDialOption, sinkWriteChunkByFiler)
 	filerSink.SetSourceFiler(filerSource)
 
-	persistEventFn := genProcessFunction(sourcePath, targetPath, sourceExcludePaths, nil, filerSink, true, debug)
+	persistEventFn := genProcessFunction(sourcePath, targetPath, sourceExcludePaths, nil, filerSink, doDeleteFiles, debug)
 
 	processEventFn := func(resp *filer_pb.SubscribeMetadataResponse) error {
 		message := resp.EventNotification