Re: NFS

On Tue, Aug 26, 2003 at 05:45:45PM -0400, Dale Heatherington wrote:
> 
> I'm not sure if this is  annoyance is a  Linux  issue of just NFS
> but it can be annoying.  I'm no expert so maybe it's pilot error.
> 
> At home I have Mandrake 7.2 on a machine used as a file server
> for a couple of other Linux boxes and a Mac OSX box.
> 
> Annoyance #1
> User numbers must match on both the server and client
> before files can be accessed.  User names don't count.
> User numbers are automatically assigned when users
> are created so will not ever match on the server and client
> unless manual editing is performed.  Several years
> ago I attempted to create a map_static file that
> was supposed to map client user numbers to server
> user numbers but it didn't work at all.

Well, NFS was the file part, NIS (Yellow pages, a trademark of the british
company responsible for those) was the user part.

You can share usernames/logins using NIS, NIS+, LDAP, Samba, etc.

> 
> Annoyance #2
> Sometimes the NFS server will go down.  All client machines
> will freeze up. They cannot even be rebooted.  The GUI freezes.
> Both Linux and the OSX clients do this.  There seems to be no timeout.

man nfs:
retry=n : number of minutes to retry an NFS mount operation, default == 1 week
bg : go to background if first mount attempt times out
soft : report error to application if a NFS operation times out
  (vs hard, the default, that just keeps retrying)

> The Server cannot be cleanly rebooted because the shutdown
> sequence attempts to shut down NFS before unmounting the
> local hard drives and fails.  It never times out.  The reset button
> must be pushed and hope the file system doesn't develop any
> hard errors.  Amazingly, if the NFS server does come back up
> after reboot the clients will un-lock and continue to work normally.

Now thats odd. I've never had any problems stopping a NFS server even with
clients connected. The "amazing" part isn't that amazing: NFS was designed
so a mount survived crashes on the server side or client side.

> Is there a reason NFS volumes are unmounted before local
> hard drives during shutdown?  I've had to hit RESET quite
> a few times due to Linux hanging forever on stoping NFS
> service and failing.

Yes, because volumes can't be unmounted if they are in use, and a NFS volume
mounted in a local directory counts as usage for that volume.

NFS shouldn't lock forever if the server is running. If it isn't, try
the options I mention above.

Regards,
Luciano Rocha