From: Dennis Nezic <dennisn-YN8wfZw00oOZ9vWoFJJngh2eb7JE58TQ@public.gmane.org>
Subject: Re: nfs: server not responding, timed out
Date: Sat, 20 Mar 2010 10:52:37 -0400
Message-ID: <20100320105237.1353566e.dennisn@dennisn.dyndns.org>
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	<20100319002720.0e93411e.dennisn@dennisn.dyndns.org>
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To: linux-nfs@vger.kernel.org
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On Fri, 19 Mar 2010 18:10:38 -0400, Dennis Nezic wrote:
> On Fri, 19 Mar 2010 00:27:20 -0400, Dennis Nezic wrote:
> > On Fri, 19 Mar 2010 10:21:57 +0800, Bian Naimeng wrote:
> > > > After upgrading my server (kernel 2.6.19 to 2.6.33, nfs-utils
> > > > 1.1.0 to 1.2.1/1.1.4/1.1.6), and probably other stuff too), and
> > > > possibly my client laptop's kernel, I have suddenly started to
> > > > get these "server X not responding, timed out" errors (on my
> > > > client), especially (only?) when doing large file transfers.
> > > > This would lead to input/output errors, and the transfers would
> > > > fail.
> > > > 
> > > > I never noticed any such problems for over two years, using the
> > > > older versions. The networking (wifi link) hasn't changed.
> > > > 
> > > > Usually the file transfer trips and falls over itself near the
> > > > end
> > > > -- Ie. it will do 600MB out of 800MB just fine, and then
> > > > suddently start giving these "timed out" errors, and then crash
> > > > and burn. At this point, I am forced to "umount -fl" the mount.
> > > > If I then try to remount it, the server acnowledges my
> > > > "authenticated mount requests" perfectly fine, but my client
> > > > (laptop) still appears "hung". After a few minutes, I am able
> > > > to remount it.
> > > > 
> > > > I tried playing with the rsize/wsize/timeo/retrans variables,
> > > > but none of it seemed to fix the problem.
> > > > 
> > > > Any ideas about what has changed? Maybe this is/was a well-known
> > > > problem? :P
> > > > 
> > > 
> > >   I do not know the what's the reason. And I am not sure the
> > > followed discussion can fix this problem, but maybe it can help
> > > you. http://marc.info/?l=linux-nfs&m=123478426412524&w=2
> > 
> > Both the patches mentioned in that thread already seem to have been
> > applied to my kernels. So, although the problem seems related, it
> > wasn't that bug in particular. The person in that thread was talking
> > about mounts dying after 5-15minutes, which doesn't happen with me
> > -- my problem only seems to occur under intense activity.
> 
> Hrm. I just noticed that my scp transfers are stalling -- which also
> didn't used to happen before with my old kernel. No error messages.
> Ftp transfers work fine. Eek. :S. (Despite the freezing/stalling, my
> *actual* network connection works perfectly.)
> 
> Ideas?

It seems that changing the mount options from "soft" to "hard" seems to
"work" -- at least the transfers eventually finish! Although there are
still stalls of 6-8minutes ... between the 16 syslog error messages:
"nfs: server XYZ not responding, still trying" and the 16 subsequent
error messages: "nfs: server XYZ OK". The key difference being that
with "hard", it is "still trying" rather than "timed out".

Now why is it stalling for so long?