linux-kernel - Re: NFS hang + umount -f: better behaviour requested.

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Message-ID: <20070821171423.GQ3956@digitalkingdom.org>
Date:	Tue, 21 Aug 2007 10:14:23 -0700
From:	Robin Lee Powell <rlpowell@...italkingdom.org>
To:	Peter Staubach <staubach@...hat.com>
Cc:	John Stoffel <john@...ffel.org>, linux-kernel@...r.kernel.org
Subject: Re: NFS hang + umount -f: better behaviour requested.

On Tue, Aug 21, 2007 at 01:01:44PM -0400, Peter Staubach wrote:
> John Stoffel wrote:
> >Robin> I'm bringing this up again (I know it's been mentioned here
> >Robin> before) because I had been told that NFS support had gotten
> >Robin> better in Linux recently, so I have been (for my $dayjob)
> >Robin> testing the behaviour of NFS (autofs NFS, specifically) under
> >Robin> Linux with hard,intr and using iptables to simulate a hang.
> >
> >So why are you mouting with hard,intr semantics?  At my current
> >SysAdmin job, we mount everything (solaris included) with
> >'soft,intr' and it works well.  If an NFS server goes down,
> >clients don't hang for large periods of time. 
> 
> Wow!  That's _really_ a bad idea.  NFS READ operations which
> timeout can lead to executables which mysteriously fail, file
> corruption, etc.  NFS WRITE operations which fail may or may not
> lead to file corruption.
> 
> Anything writable should _always_ be mounted "hard" for safety
> purposes.  Readonly mounted file systems _may_ be mounted "soft",
> depending upon what is located on them.

Does write + tcp make this any different?

-Robin

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