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Date:   Thu, 6 Apr 2023 17:54:09 +0200
From:   Christian Herzog <herzog@phys.ethz.ch>
To:     Chuck Lever III <chuck.lever@oracle.com>
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: file server freezes with all nfsds stuck in D state after
 upgrade to Debian bookworm
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Reply-To: Christian Herzog <herzog@phys.ethz.ch>
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Dear Chuck,

> > That was our first idea too, but we haven't found any indication that this is the case. The xfs file systems seem perfectly fine when all nfsds are in D state, and we can
> > read from them and write to them. If xfs were to block nfs IO, this should
> > affect other processes too, right?
> 
> It's possible that the NFSD threads are waiting on I/O to a particular filesystem block. XFS is not likely to block other activity in this case.
ok good to know. So far we were under the impression that a file system would
block as a whole.

> I'm merely suggesting that you should start troubleshooting at the bottom of the stack instead of the top. The wait is far outside the realm of NFSD.
thanks, point taken. So next time it happens we'll make sure to poke in this
direction during the few minutes we have for debugging before we get tarred
and feathered by the users.


-Christian


-- 
Dr. Christian Herzog <herzog@phys.ethz.ch>  support: +41 44 633 26 68
Head, IT Services Group, HPT H 8              voice: +41 44 633 39 50
Department of Physics, ETH Zurich           
8093 Zurich, Switzerland                     http://isg.phys.ethz.ch/