diff --git a/weed/command/mount.go b/weed/command/mount.go
index 151c6bedf..f0514b93a 100644
--- a/weed/command/mount.go
+++ b/weed/command/mount.go
@@ -1,10 +1,11 @@
 package command
 
 type MountOptions struct {
-	filer       *string
-	dir         *string
-	collection  *string
-	replication *string
+	filer            *string
+	dir              *string
+	collection       *string
+	replication      *string
+	chunkSizeLimitMB *int
 }
 
 var (
@@ -13,11 +14,11 @@ var (
 
 func init() {
 	cmdMount.Run = runMount // break init cycle
-	cmdMount.IsDebug = cmdMount.Flag.Bool("debug", false, "verbose debug information")
 	mountOptions.filer = cmdMount.Flag.String("filer", "localhost:8888", "weed filer location")
 	mountOptions.dir = cmdMount.Flag.String("dir", ".", "mount weed filer to this directory")
 	mountOptions.collection = cmdMount.Flag.String("collection", "", "collection to create the files")
 	mountOptions.replication = cmdMount.Flag.String("replication", "000", "replication to create to files")
+	mountOptions.chunkSizeLimitMB = cmdMount.Flag.Int("chunkSizeLimitMB", 0, "if set, limit the chunk size in MB")
 }
 
 var cmdMount = &Command{
diff --git a/weed/command/mount_std.go b/weed/command/mount_std.go
index fcf663e1c..7e7a35f3d 100644
--- a/weed/command/mount_std.go
+++ b/weed/command/mount_std.go
@@ -48,7 +48,7 @@ func runMount(cmd *Command, args []string) bool {
 	})
 
 	err = fs.Serve(c, filesys.NewSeaweedFileSystem(
-		*mountOptions.filer, *mountOptions.collection, *mountOptions.replication))
+		*mountOptions.filer, *mountOptions.collection, *mountOptions.replication, *mountOptions.chunkSizeLimitMB))
 	if err != nil {
 		fuse.Unmount(*mountOptions.dir)
 	}
diff --git a/weed/filesys/dirty_page.go b/weed/filesys/dirty_page.go
index da442d6c6..a78fdb47d 100644
--- a/weed/filesys/dirty_page.go
+++ b/weed/filesys/dirty_page.go
@@ -59,7 +59,13 @@ func (pages *ContinuousDirtyPages) AddPage(ctx context.Context, offset int64, da
 			Offset: offset,
 			Data:   data,
 		})
-		return nil, nil
+
+		if pages.totalSize() >= pages.f.wfs.chunkSizeLimit {
+			chunk, err = pages.saveToStorage(ctx)
+			pages.pages = nil
+			glog.V(3).Infof("%s/%s add split [%d,%d)", pages.f.dir.Path, pages.f.Name, chunk.Offset, chunk.Offset+int64(chunk.Size))
+		}
+		return
 	}
 
 	chunk, err = pages.saveToStorage(ctx)
diff --git a/weed/filesys/wfs.go b/weed/filesys/wfs.go
index b9cb0210b..4b9e20b95 100644
--- a/weed/filesys/wfs.go
+++ b/weed/filesys/wfs.go
@@ -13,14 +13,16 @@ type WFS struct {
 	listDirectoryEntriesCache *ccache.Cache
 	collection                string
 	replication               string
+	chunkSizeLimit            int64
 }
 
-func NewSeaweedFileSystem(filer string, collection string, replication string) *WFS {
+func NewSeaweedFileSystem(filer string, collection string, replication string, chunkSizeLimitMB int) *WFS {
 	return &WFS{
 		filer:                     filer,
 		listDirectoryEntriesCache: ccache.New(ccache.Configure().MaxSize(6000).ItemsToPrune(100)),
 		collection:                collection,
 		replication:               replication,
+		chunkSizeLimit:            int64(chunkSizeLimitMB) * 1024 * 1024,
 	}
 }