linux-kernel - Re: [Qemu-devel] Massive read only kvm guests when backing file was missing

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Date:	Fri, 28 Mar 2014 11:01:00 +0400
From:	Michael Tokarev <mjt@....msk.ru>
To:	Alejandro Comisario <alejandro.comisario@...cadolibre.com>
CC:	Stefan Hajnoczi <stefanha@...il.com>, qemu-devel@...gnu.org,
	kvm@...r.kernel.org, "Michael S. Tsirkin" <mst@...hat.com>,
	ghammer@...hat.com, Jason Wang <jasowang@...hat.com>,
	linux-kernel@...r.kernel.org, Markus Armbruster <armbru@...hat.com>
Subject: Re: [Qemu-devel] Massive read only kvm guests when backing file was
 missing

27.03.2014 20:14, Alejandro Comisario wrote:
> Seems like virtio (kvm 1.0) doesnt expose timeout on the guest side
> (ubuntu 12.04 on host and guest).
> So, how can i adjust the tinmeout on the guest ?

After a bit more talks on IRC yesterday, it turned out that the situation
is _much_ more "interesting" than originally described.  The OP claims to
have 10500 guests running off an NFS server, and that after NFS server
downtime, the "backing files" were disappeared (whatever it means), so
they had to restore those files.  More, the OP didn't even bother to look
at the guest's dmesg, being busy rebooting all 10500 guests.

> This solution is the most logical one, but i cannot apply it!
> thanks for all the responses!

I suggested the OP to actually describe the _real_ situation, instead of
giving random half-pictures, and actually take a look at the actual problem
as reported in various places (most importantly the guest kernel log), and
reoirt _those_ hints to the list.  I also mentioned that, at least for some
NFS servers, if a client has a file open on the server, and this file is
deleted, the server will report error to the client when client tries to
access that file, and this has nothing at all to do with timeouts of any
kind.

Thanks,

/mjt
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