December 23, 2013
In the last weeks I was working (from time to time 😉 ) on a new setup of my NAS at home. During this I learn some stuff I didn’t know about NFS which I want to share here. I assume that you got the basis NFS stuff working or know how it works and want some addition tips and ticks
- How to query a NFS server for the exported directories and the settings? Easy, use
showmount -e <servername>. Here an example:
$ showmount -e 10.x.x.x
Export list for 10.x.x.x:
- Use fsid – why?
- NFS needs to be able to identify each filesystem that it exports. Normally it will use a UUID for the filesystem (if the filesystem has such a thing) or the device number of the device holding the filesystem (if the filesystem is stored on the device). If you want to an export different file system (e.g. replacement HDD) the fsid changes and you’re clients have to remount (as they have a stale NFS mount). Read more on this topic here.
- Some file systems don’t have a UUID, e.g. encfs does not … use a separate fsid for each export!
- You can export multiple file system with one mount request by the client, if you use nohide. Normally, if a server exports two file systems one of which is mounted on the other, then the client will have to mount both file systems explicitly to get access to them. If it just mounts the parent, it will see an empty directory at the place where the other file system is mounted. That file system is “hidden” – if you don’t want that use nohide, like in this example:
- If you changed
/etc/exportsyou don’t need to restart your NFS daemon. If the init script provides a reload thats good – if not use
So far that are my new learned tips and tricks … I think there was one more but I can’t remember it now. Will add it later if I remember.