Updated Mount Remote Storage (markdown)

Mount-Remote-Storage.md

@@ -3,6 +3,15 @@ After [[Configure Remote Storage]], you will get a storage name `cloud1`.
 ## Mount a Remote Storage
 Now you can run `remote.mount` in `weed shell`:
 ```
+> remote.mount -h
+Usage of remote.mount:
+  -dir string
+    	a directory in filer
+  -nonempty
+    	allows the mounting over a non-empty directory
+  -remote string
+    	a directory in remote storage, ex. <storageName>/<bucket>/path/to/dir
+
 > help remote.mount
   remote.mount	# mount remote storage and pull its metadata
 
@@ -27,6 +36,17 @@ This operation will pull down all metadata from the remote storage.
 
 Later, any metadata operations can be invoked locally, and respond very fast.
 
+`unmount` will drop all local metadata and cached file content.
+
+### Repeatedly Update Metadata
+Sometimes the data on the cloud has changed and local metadata becomes stale. To `unmount` first and `mount` again is costly since all data has to be cached again. To refresh the metadata changes, you can simply re-run the same command with `-nonempty` option, e.g.:
+```
+	remote.mount -dir=xxx -remote=cloud1/bucket -nonempty
+```
+This will update local metadata accordingly and still keep file contents that are not changed.
+
+If the data on the cloud is changed often, you can add this command to the admin scripts defined in `master.toml`, to run it regularly.
+
 ## Write Back changes to Remote Storage
 
 If the mounted directory is only for reading, you can start to use it.