ensure 30GB or less

avoid https://github.com/chrislusf/seaweedfs/issues/535

weed/command/master.go

@@ -65,6 +65,9 @@ func runMaster(cmd *Command, args []string) bool {
 	if *masterWhiteListOption != "" {
 		masterWhiteList = strings.Split(*masterWhiteListOption, ",")
 	}
+	if *volumeSizeLimitMB > 30*1000 {
+		glog.Fatalf("volumeSizeLimitMB should be smaller than 30000")
+	}
 
 	r := mux.NewRouter()
 	ms := weed_server.NewMasterServer(r, *mport, *metaFolder,

weed/command/server.go

@@ -151,6 +151,10 @@ func runServer(cmd *Command, args []string) bool {
 		}
 	}
 
+	if *masterVolumeSizeLimitMB > 30*1000 {
+		glog.Fatalf("masterVolumeSizeLimitMB should be less than 30000")
+	}
+
 	if *masterMetaFolder == "" {
 		*masterMetaFolder = folders[0]
 	}