[PLUG] How to umount NFS hung mouts

[Mark Martin]

On Wednesday 13 August 2003 13:50, Russ Johnson wrote:
> * Jeff Schwaber <freyley at gmx.net> [2003-08-13 13:42]:
> > On Wed, 2003-08-13 at 13:20, Russ Johnson wrote:
> > > * Alex Daniloff <alex at daniloff.com> [2003-08-13 09:44]:
> > > > Could somebody tell me please
> > > > how to safely umount locally mounted NFS share
> > > > when remote NFS server is down?
> > > > Rebooting local machine is not an option in my case.
> > >
> > > This is the reason that I've been shying away from Linux for file
> > > serving. If an NFS server (linux) goes down, then you end up with stale
> > > mounts.
> >
> > What's a better solution?
>
> I've been using Solaris where I can. I have lots of automounted file
> systems, and sometimes, the file server just has to bounce...
>
> With Linux, I was guaranteed to be chasing stale NFS mounts for the rest
> of the day. I switched to Solaris, and things come back, and the mounts
> start working again. The process using them may block while the server
> is actually rebooting, but as soon as the server comes back, it
> continues as if nothing happened.
>
> I've only used Solaris on Sparc hardware for this. I have not tested to
> see if Solaris on x86 is as good during a bounce. Let me pencil that
> test into my schedule. :)

According to the NFS HOWTO, if the offending filesystem was mounted with the 
"hard" option, intentionally or otherwise, the mount should come back once 
the NFS server is back up under Linux too.  Also, according to the HOWTO, the 
danger of using soft mounts is that programs doing I/O on the filesystem are 
likely not to handle timeouts on the filesystem well -- hence corruption and 
lost files.  This is not the fault of NFS under Linux.  It's the fault of the 
myriad programs that weren't written to consider the case of having the 
filesystem ripped out from under them.  Again, I am merely paraphasing from 
the HOWTO (although I tested many of these things out quite a few years ago 
myself).

-- 
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Mark A. Martin, Ph.D.
Applied Mathematics -- Software Development -- Systems Administration
Currently available for employment.
See http://www.amath.washington.edu/~mmartin/resume/ for details.
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