on 10:23 Wed 26 Jan, Rudi Ahlers (Rudi@SoftDux.com) wrote:
Hi All,
How do I unmount an NFS share when the NFS server is unaivalable?
I tried "umount /bck" but it "hangs" indefinitely "umount -f /bck" tells me the mount if busy and I can't unmount it:
root@saturn:[~]$ umount -f /bck umount2: Device or resource busy umount: /bck: device is busy umount2: Device or resource busy umount: /bck: device is busy
This non-working NFS share is causing problems on the server and I need to unmount it until such a time when the NFS server (faulty NAS) is repaired.
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.