diff --git a/go/operation/assign_file_id.go b/go/operation/assign_file_id.go
index a6680cbb8..4941d3c86 100644
--- a/go/operation/assign_file_id.go
+++ b/go/operation/assign_file_id.go
@@ -17,12 +17,15 @@ type AssignResult struct {
 	Error     string `json:"error"`
 }
 
-func Assign(server string, count int, replication string) (*AssignResult, error) {
+func Assign(server string, count int, replication string, collection string) (*AssignResult, error) {
 	values := make(url.Values)
 	values.Add("count", strconv.Itoa(count))
 	if replication != "" {
 		values.Add("replication", replication)
 	}
+	if collection != "" {
+		values.Add("collection", collection)
+	}
 	jsonBlob, err := util.Post("http://"+server+"/dir/assign", values)
 	glog.V(2).Info("assign result :", string(jsonBlob))
 	if err != nil {
diff --git a/go/operation/submit.go b/go/operation/submit.go
index 814c64957..693b90db1 100644
--- a/go/operation/submit.go
+++ b/go/operation/submit.go
@@ -12,14 +12,16 @@ import (
 )
 
 type FilePart struct {
-	Reader    io.Reader
-	FileName  string
-	FileSize  int64
-	IsGzipped bool
-	MimeType  string
-	ModTime   int64  //in seconds
-	Server    string //this comes from assign result
-	Fid       string //this comes from assign result, but customizable
+	Reader      io.Reader
+	FileName    string
+	FileSize    int64
+	IsGzipped   bool
+	MimeType    string
+	ModTime     int64 //in seconds
+	Replication string
+	Collection  string
+	Server      string //this comes from assign result
+	Fid         string //this comes from assign result, but customizable
 }
 
 type SubmitResult struct {
@@ -30,12 +32,12 @@ type SubmitResult struct {
 	Error    string `json:"error"`
 }
 
-func SubmitFiles(master string, files []FilePart, replication string, maxMB int) ([]SubmitResult, error) {
+func SubmitFiles(master string, files []FilePart, replication string, collection string, maxMB int) ([]SubmitResult, error) {
 	results := make([]SubmitResult, len(files))
 	for index, file := range files {
 		results[index].FileName = file.FileName
 	}
-	ret, err := Assign(master, len(files), replication)
+	ret, err := Assign(master, len(files), replication, collection)
 	if err != nil {
 		for index, _ := range files {
 			results[index].Error = err.Error()
@@ -48,7 +50,9 @@ func SubmitFiles(master string, files []FilePart, replication string, maxMB int)
 			file.Fid = file.Fid + "_" + strconv.Itoa(index)
 		}
 		file.Server = ret.PublicUrl
-		results[index].Size, err = file.Upload(maxMB, master, replication)
+		file.Replication = replication
+		file.Collection = collection
+		results[index].Size, err = file.Upload(maxMB, master)
 		if err != nil {
 			results[index].Error = err.Error()
 		}
@@ -95,7 +99,7 @@ func newFilePart(fullPathFilename string) (ret FilePart, err error) {
 	return ret, nil
 }
 
-func (fi FilePart) Upload(maxMB int, master, replication string) (retSize int, err error) {
+func (fi FilePart) Upload(maxMB int, master string) (retSize int, err error) {
 	fileUrl := "http://" + fi.Server + "/" + fi.Fid
 	if fi.ModTime != 0 {
 		fileUrl += "?ts=" + strconv.Itoa(int(fi.ModTime))
@@ -108,7 +112,7 @@ func (fi FilePart) Upload(maxMB int, master, replication string) (retSize int, e
 		chunks := fi.FileSize/chunkSize + 1
 		fids := make([]string, 0)
 		for i := int64(0); i < chunks; i++ {
-			id, count, e := upload_one_chunk(fi.FileName+"-"+strconv.FormatInt(i+1, 10), io.LimitReader(fi.Reader, chunkSize), master, replication)
+			id, count, e := upload_one_chunk(fi.FileName+"-"+strconv.FormatInt(i+1, 10), io.LimitReader(fi.Reader, chunkSize), master, fi.Replication, fi.Collection)
 			if e != nil {
 				return 0, e
 			}
@@ -126,8 +130,8 @@ func (fi FilePart) Upload(maxMB int, master, replication string) (retSize int, e
 	return
 }
 
-func upload_one_chunk(filename string, reader io.Reader, master, replication string) (fid string, size int, e error) {
-	ret, err := Assign(master, 1, replication)
+func upload_one_chunk(filename string, reader io.Reader, master, replication string, collection string) (fid string, size int, e error) {
+	ret, err := Assign(master, 1, replication, collection)
 	if err != nil {
 		return "", 0, err
 	}
diff --git a/go/weed/benchmark.go b/go/weed/benchmark.go
index f9a775c32..2fc83e578 100644
--- a/go/weed/benchmark.go
+++ b/go/weed/benchmark.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"math/rand"
 	"os"
 	"strings"
 	"sync"
@@ -15,14 +16,16 @@ import (
 )
 
 type BenchmarkOptions struct {
-	server        *string
-	concurrency   *int
-	numberOfFiles *int
-	fileSize      *int
-	idListFile    *string
-	write         *bool
-	read          *bool
-	vid2server    map[string]string //cache for vid locations
+	server         *string
+	concurrency    *int
+	numberOfFiles  *int
+	fileSize       *int
+	idListFile     *string
+	write          *bool
+	read           *bool
+	sequentialRead *bool
+	collection     *string
+	vid2server     map[string]string //cache for vid locations
 }
 
 var (
@@ -39,6 +42,8 @@ func init() {
 	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.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")
 }
 
 var cmdBenchmark = &Command{
@@ -120,9 +125,9 @@ func writeFiles(idChan chan int, fileIdLineChan chan string, s *stats) {
 		if id, ok := <-idChan; ok {
 			start := time.Now()
 			fp := &operation.FilePart{Reader: &FakeReader{id: uint64(id), size: int64(*b.fileSize)}, FileSize: int64(*b.fileSize)}
-			if assignResult, err := operation.Assign(*b.server, 1, ""); err == nil {
-				fp.Server, fp.Fid = assignResult.PublicUrl, assignResult.Fid
-				fp.Upload(0, *b.server, "")
+			if assignResult, err := operation.Assign(*b.server, 1, "", *b.collection); err == nil {
+				fp.Server, fp.Fid, fp.Collection = assignResult.PublicUrl, assignResult.Fid, *b.collection
+				fp.Upload(0, *b.server)
 				writeStats.addSample(time.Now().Sub(start))
 				fileIdLineChan <- fp.Fid
 				s.transferred += int64(*b.fileSize)
@@ -212,13 +217,28 @@ func readFileIds(fileName string, fileIdLineChan chan string) {
 	defer file.Close()
 
 	r := bufio.NewReader(file)
-	for {
-		if line, err := Readln(r); err == nil {
-			fileIdLineChan <- string(line)
-		} else {
-			break
+	if *b.sequentialRead {
+		for {
+			if line, err := Readln(r); err == nil {
+				fileIdLineChan <- string(line)
+			} else {
+				break
+			}
+		}
+	} else {
+		lines := make([]string, 0, *b.numberOfFiles)
+		for {
+			if line, err := Readln(r); err == nil {
+				lines = append(lines, string(line))
+			} else {
+				break
+			}
+		}
+		for i := 0; i < *b.numberOfFiles; i++ {
+			fileIdLineChan <- lines[rand.Intn(len(lines))]
 		}
 	}
+
 	close(fileIdLineChan)
 }
 
diff --git a/go/weed/upload.go b/go/weed/upload.go
index 42e753981..b59313a2a 100644
--- a/go/weed/upload.go
+++ b/go/weed/upload.go
@@ -10,6 +10,7 @@ import (
 
 var (
 	uploadReplication *string
+	uploadCollection  *string
 	uploadDir         *string
 	include           *string
 	maxMB             *int
@@ -21,7 +22,8 @@ func init() {
 	server = cmdUpload.Flag.String("server", "localhost:9333", "weedfs master location")
 	uploadDir = cmdUpload.Flag.String("dir", "", "Upload the whole folder recursively if specified.")
 	include = cmdUpload.Flag.String("include", "", "pattens of files to upload, e.g., *.pdf, *.html, ab?d.txt, works together with -dir")
-	uploadReplication = cmdUpload.Flag.String("replication", "", "replication type(000,001,010,100,110,200)")
+	uploadReplication = cmdUpload.Flag.String("replication", "", "replication type")
+	uploadCollection = cmdUpload.Flag.String("collection", "", "optional collection name")
 	maxMB = cmdUpload.Flag.Int("maxMB", 0, "split files larger than the limit")
 }
 
@@ -65,7 +67,7 @@ func runUpload(cmd *Command, args []string) bool {
 					if e != nil {
 						return e
 					}
-					results, e := operation.SubmitFiles(*server, parts, *uploadReplication, *maxMB)
+					results, e := operation.SubmitFiles(*server, parts, *uploadReplication, *uploadCollection, *maxMB)
 					bytes, _ := json.Marshal(results)
 					fmt.Println(string(bytes))
 					if e != nil {
@@ -82,7 +84,7 @@ func runUpload(cmd *Command, args []string) bool {
 		if e != nil {
 			fmt.Println(e.Error())
 		}
-		results, _ := operation.SubmitFiles(*server, parts, *uploadReplication, *maxMB)
+		results, _ := operation.SubmitFiles(*server, parts, *uploadReplication, *uploadCollection, *maxMB)
 		bytes, _ := json.Marshal(results)
 		fmt.Println(string(bytes))
 	}
diff --git a/go/weed/weed_server/common.go b/go/weed/weed_server/common.go
index d0d52f488..d4492e719 100644
--- a/go/weed/weed_server/common.go
+++ b/go/weed/weed_server/common.go
@@ -94,7 +94,7 @@ func submitForClientHandler(w http.ResponseWriter, r *http.Request, masterUrl st
 	}
 
 	debug("assigning file id for", fname)
-	assignResult, ae := operation.Assign(masterUrl, 1, r.FormValue("replication"))
+	assignResult, ae := operation.Assign(masterUrl, 1, r.FormValue("replication"), r.FormValue("collection"))
 	if ae != nil {
 		writeJsonError(w, r, ae)
 		return