Kill NFS connection

[Andrew Falanga]

On Monday 08 September 2008 13:01:08 patrick wrote:
> Is there a way to kill an NFS connection to a server that's stopped
> responding? When I try to simply unmount it, I get a never-ending
> stream of "server not responding" messages. (Using FreeBSD 6.2, BTW.)
>
> Thanks,
>
> Patrick
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Another respondent already mentioned "umount -f ..."  I wanted to clear up 
something you may, or may not, know about NFS and that is that there isn't 
really a connection.  Unless the behaviour changed in FBSD 7, when mounting 
NFS; UDP is used.  UDP is a connectionless protocol in the IP suite of 
protocols.  Because of this, detecting a lost "connection" is rather 
problematic.  Usually, timeouts are used when sending new information, or 
requesting something from the server.

I'd read through the mount_nfs(8) manual page just to be sure of options that 
may help out in this case.  The -c -t -D and some others looked rather 
promising.  In my experience, it's usually pretty difficult to unmount an 
unresponsive NFS mount.  In fact, *and only because of the environment in 
which I was working*, I usually ended up rebooting my box.  This is because I 
didn't want to wait for the timeouts (painfully slow in some default 
configurations; upwards of 10 minutes or more).  This probably isn't feasible 
if your system hosts services for other clients.

Andy