[PLUG] How to umount NFS hung mouts

[Paul Heinlein]

On Wed, 13 Aug 2003, Steven A. Adams wrote:

> If you can use the umount -f option to force the operation I would
> suggest rewriting the fstab entry for this mount to include the soft
> and timeo= nfs options (see man mount). This way if the nfs server
> ever does this again it will allow the workstation to gracefully
> recover from the event.

I would highly suggest that you investigate the soft and timeo mount
options very, very carefully before implementing either of them. It's
been repeatedly stated on the NFS mailing list that you leave yourself
open to silent data corruption when using soft mounts. Here's a
representative opinion:

  Having NFS timeout underneath you is exactly the same as having a
  hard drive fail underneath you. Most if not all applications are
  utterly unprepared to deal with the resulting I/O errors, thus
  guaranteeing data corruption.

  The 'soft' mounting is only acceptable for read-only mounts, and
  even then only if you really don't care about your input data
  disappearing at random. That's AT RANDOM -- it's not a typo, you'll
  get RANDOM failures, depending on how loaded your network and/or
  server are at times.

--Paul Heinlein <heinlein at madboa.com>