diff --git a/weed/command/benchmark.go b/weed/command/benchmark.go
index a73a4e81c..5b2e31622 100644
--- a/weed/command/benchmark.go
+++ b/weed/command/benchmark.go
@@ -42,6 +42,7 @@ type BenchmarkOptions struct {
 	grpcDialOption   grpc.DialOption
 	masterClient     *wdclient.MasterClient
 	grpcRead         *bool
+	fsync            *bool
 }
 
 var (
@@ -67,6 +68,7 @@ func init() {
 	b.cpuprofile = cmdBenchmark.Flag.String("cpuprofile", "", "cpu profile output file")
 	b.maxCpu = cmdBenchmark.Flag.Int("maxCpu", 0, "maximum number of CPUs. 0 means all available CPUs")
 	b.grpcRead = cmdBenchmark.Flag.Bool("grpcRead", false, "use grpc API to read")
+	b.fsync = cmdBenchmark.Flag.Bool("fsync", false, "flush data to disk after write")
 	sharedBytes = make([]byte, 1024)
 }
 
@@ -230,6 +232,7 @@ func writeFiles(idChan chan int, fileIdLineChan chan string, s *stat) {
 			Reader:   &FakeReader{id: uint64(id), size: fileSize, random: random},
 			FileSize: fileSize,
 			MimeType: "image/bench", // prevent gzip benchmark content
+			Fsync: *b.fsync,
 		}
 		ar := &operation.VolumeAssignRequest{
 			Count:       1,
diff --git a/weed/operation/submit.go b/weed/operation/submit.go
index d1c4706ce..7cf5b9645 100644
--- a/weed/operation/submit.go
+++ b/weed/operation/submit.go
@@ -27,6 +27,7 @@ type FilePart struct {
 	Ttl         string
 	Server      string //this comes from assign result
 	Fid         string //this comes from assign result, but customizable
+	Fsync       bool      
 }
 
 type SubmitResult struct {
@@ -116,6 +117,9 @@ func (fi FilePart) Upload(maxMB int, master string, usePublicUrl bool, jwt secur
 	if fi.ModTime != 0 {
 		fileUrl += "?ts=" + strconv.Itoa(int(fi.ModTime))
 	}
+	if fi.Fsync {
+		fileUrl += "?fsync=true"
+	}
 	if closer, ok := fi.Reader.(io.Closer); ok {
 		defer closer.Close()
 	}