diff --git a/go/weed/benchmark.go b/go/weed/benchmark.go
index 173900c4f..5c83314e4 100644
--- a/go/weed/benchmark.go
+++ b/go/weed/benchmark.go
@@ -19,17 +19,18 @@ import (
 )
 
 type BenchmarkOptions struct {
-	server         *string
-	concurrency    *int
-	numberOfFiles  *int
-	fileSize       *int
-	idListFile     *string
-	write          *bool
-	read           *bool
-	sequentialRead *bool
-	collection     *string
-	cpuprofile     *string
-	vid2server     map[string]string //cache for vid locations
+	server           *string
+	concurrency      *int
+	numberOfFiles    *int
+	fileSize         *int
+	idListFile       *string
+	write            *bool
+	deletePercentage *int
+	read             *bool
+	sequentialRead   *bool
+	collection       *string
+	cpuprofile       *string
+	vid2server       map[string]string //cache for vid locations
 }
 
 var (
@@ -41,10 +42,11 @@ func init() {
 	cmdBenchmark.IsDebug = cmdBenchmark.Flag.Bool("debug", false, "verbose debug information")
 	b.server = cmdBenchmark.Flag.String("server", "localhost:9333", "weedfs master location")
 	b.concurrency = cmdBenchmark.Flag.Int("c", 16, "number of concurrent write or read processes")
-	b.fileSize = cmdBenchmark.Flag.Int("size", 1024, "simulated file size in bytes")
+	b.fileSize = cmdBenchmark.Flag.Int("size", 1024, "simulated file size in bytes, with random(0~63) bytes padding")
 	b.numberOfFiles = cmdBenchmark.Flag.Int("n", 1024*1024, "number of files to write for each thread")
 	b.idListFile = cmdBenchmark.Flag.String("list", os.TempDir()+"/benchmark_list.txt", "list of uploaded file ids")
 	b.write = cmdBenchmark.Flag.Bool("write", true, "enable write")
+	b.deletePercentage = cmdBenchmark.Flag.Int("deletePercent", 0, "the percent of writes that are deletes")
 	b.read = cmdBenchmark.Flag.Bool("read", true, "enable read")
 	b.sequentialRead = cmdBenchmark.Flag.Bool("readSequentially", false, "randomly read by ids from \"-list\" specified file")
 	b.collection = cmdBenchmark.Flag.String("collection", "benchmark", "write data to this collection")
@@ -85,11 +87,16 @@ var cmdBenchmark = &Command{
 }
 
 var (
-	wait       sync.WaitGroup
-	writeStats *stats
-	readStats  *stats
+	wait            sync.WaitGroup
+	writeStats      *stats
+	readStats       *stats
+	serverLimitChan map[string]chan bool
 )
 
+func init() {
+	serverLimitChan = make(map[string]chan bool)
+}
+
 func runbenchmark(cmd *Command, args []string) bool {
 	fmt.Printf("This is Weed File System version %s %s %s\n", VERSION, runtime.GOOS, runtime.GOARCH)
 	if *b.cpuprofile != "" {
@@ -123,6 +130,7 @@ func bench_write() {
 		go writeFiles(idChan, fileIdLineChan, writeStats)
 	}
 	writeStats.start = time.Now()
+	writeStats.total = *b.numberOfFiles
 	go writeStats.checkProgress("Writing Benchmark", finishChan)
 	for i := 0; i < *b.numberOfFiles; i++ {
 		idChan <- i
@@ -145,6 +153,7 @@ func bench_read() {
 	wait.Add(*b.concurrency)
 	go readFileIds(*b.idListFile, fileIdLineChan)
 	readStats.start = time.Now()
+	readStats.total = *b.numberOfFiles
 	go readStats.checkProgress("Randomly Reading Benchmark", finishChan)
 	for i := 0; i < *b.concurrency; i++ {
 		go readFiles(fileIdLineChan, readStats)
@@ -157,7 +166,6 @@ func bench_read() {
 }
 
 func writeFiles(idChan chan int, fileIdLineChan chan string, s *stats) {
-	serverLimitChan := make(map[string]chan bool)
 	for {
 		if id, ok := <-idChan; ok {
 			start := time.Now()
@@ -170,7 +178,21 @@ func writeFiles(idChan chan int, fileIdLineChan chan string, s *stats) {
 				}
 				serverLimitChan[fp.Server] <- true
 				if _, err := fp.Upload(0, *b.server); err == nil {
-					fileIdLineChan <- fp.Fid
+					if rand.Intn(100) < *b.deletePercentage {
+						s.total++
+						go func() {
+							time.Sleep(time.Duration(rand.Intn(1000)) * time.Millisecond)
+							serverLimitChan[fp.Server] <- true
+							if e := operation.DeleteFile(*b.server, fp.Fid); e == nil {
+								s.completed++
+							} else {
+								s.failed++
+							}
+							<-serverLimitChan[fp.Server]
+						}()
+					} else {
+						fileIdLineChan <- fp.Fid
+					}
 					s.completed++
 					s.transferred += fileSize
 				} else {
@@ -189,6 +211,8 @@ func writeFiles(idChan chan int, fileIdLineChan chan string, s *stats) {
 			break
 		}
 	}
+	//wait for the deleting goroutines
+	time.Sleep(time.Duration(1500) * time.Millisecond)
 	wait.Done()
 }
 
@@ -291,8 +315,10 @@ func readFileIds(fileName string, fileIdLineChan chan string) {
 				break
 			}
 		}
-		for i := 0; i < *b.numberOfFiles; i++ {
-			fileIdLineChan <- lines[rand.Intn(len(lines))]
+		if len(lines) > 0 {
+			for i := 0; i < *b.numberOfFiles; i++ {
+				fileIdLineChan <- lines[rand.Intn(len(lines))]
+			}
 		}
 	}
 
@@ -310,6 +336,7 @@ type stats struct {
 	overflow    []int
 	completed   int
 	failed      int
+	total       int
 	transferred int64
 	start       time.Time
 	end         time.Time
@@ -343,7 +370,7 @@ func (s *stats) checkProgress(testName string, finishChan chan bool) {
 		case t := <-ticker:
 			completed, transferred, taken := s.completed-lastCompleted, s.transferred-lastTransferred, t.Sub(lastTime)
 			fmt.Printf("Completed %d of %d requests, %3.1f%% %3.1f/s %3.1fMB/s\n",
-				s.completed, *b.numberOfFiles, float64(s.completed)*100/float64(*b.numberOfFiles),
+				s.completed, s.total, float64(s.completed)*100/float64(s.total),
 				float64(completed)*float64(int64(time.Second))/float64(int64(taken)),
 				float64(transferred)*float64(int64(time.Second))/float64(int64(taken))/float64(1024*1024),
 			)