diff --git a/weed/command/mount.go b/weed/command/mount.go
index fefc4ff53..440aca8c6 100644
--- a/weed/command/mount.go
+++ b/weed/command/mount.go
@@ -40,8 +40,8 @@ func init() {
 	mountOptions.replication = cmdMount.Flag.String("replication", "", "replication(e.g. 000, 001) to create to files. If empty, let filer decide.")
 	mountOptions.ttlSec = cmdMount.Flag.Int("ttl", 0, "file ttl in seconds")
 	mountOptions.chunkSizeLimitMB = cmdMount.Flag.Int("chunkSizeLimitMB", 16, "local write buffer size, also chunk large files")
-	mountOptions.cacheDir = cmdMount.Flag.String("cacheDir", os.TempDir(), "local cache directory for file chunks")
-	mountOptions.cacheSizeMB = cmdMount.Flag.Int64("cacheCapacityMB", 1000, "local cache capacity in MB (0 will disable cache)")
+	mountOptions.cacheDir = cmdMount.Flag.String("cacheDir", os.TempDir(), "local cache directory for file chunks and meta data")
+	mountOptions.cacheSizeMB = cmdMount.Flag.Int64("cacheCapacityMB", 1000, "local file chunk cache capacity in MB (0 will disable cache)")
 	mountOptions.dataCenter = cmdMount.Flag.String("dataCenter", "", "prefer to write to the data center")
 	mountOptions.allowOthers = cmdMount.Flag.Bool("allowOthers", true, "allows other users to access the file system")
 	mountOptions.umaskString = cmdMount.Flag.String("umask", "022", "octal umask, e.g., 022, 0111")