[CentOS] how to unmount an NFS share when the NFS server is unavailable?

Wed Jan 26 23:26:13 UTC 2011
Les Mikesell <lesmikesell at gmail.com>

On 1/26/2011 4:55 PM, Dr. Ed Morbius wrote:
> The specific solution is 'umount -fl<dir|device>'.
> The general solution's a little stickier.
> I'd suggest the automount route as well (you're only open to NFS issues
> while the filesystem is mounted), but you then have to maintain
> automount maps and run the risk of issues with the automounter (I've
> seen large production environments in which the OOM killer would
> arbitrarily select processes to kill ....).
> Monitoring of client and server NFS processes helps.  If it's the filer
> heads which are failing, and need warrants it, look into HA failover
> options.
> Soft mounts as mentioned won't hange processes, but may result in data
> loss.  This is most critical in database operations (where atomicity is
> assumed and generally assured by the DBMS).  If the issue is one of
> re-running a backup job, and you can get a clear failure, risk would be
> generally mitigated.

Actually, since the original question involved access to backups, I 
should have given my usual answer which is that backuppc is the thing to 
use for backups and it provides a web interface for restores (you pick 
the historical version you want and either tell it to put it back to the 
original host or you can download a tarball through the browser). Very 
nice for self-serve access.  It does want to map complete hosts to 
owners that have permission to access them but with a little work you 
make different areas of a shared system look like separate hosts.

   Les Mikesell
    lesmikesell at gmail.com