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Date: Wed, 09 Nov 2011 10:39:11 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] qemu and qemu.git -> Migration + disk stress
 introduces qcow2 corruptions
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To: Lucas Meneghel Rodrigues <lmr@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, KVM mailing list <kvm@vger.kernel.org>, "Michael S. Tsirkin" <mst@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>, QEMU devel <qemu-devel@nongnu.org>, Juan Jose Quintela Carreira <quintela@redhat.com>, Avi Kivity <avi@redhat.com>

On 11/09/2011 10:29 AM, Lucas Meneghel Rodrigues wrote:
> Hi guys, here I am, reporting yet another issue with qemu. This time, it's
> something that was first reported in January, and Juan proposed a patch for it:
>
> http://comments.gmane.org/gmane.comp.emulators.qemu/89009

Migration with qcow2 is not a supported feature for 1.0.  Migration is only 
supported with raw images using coherent shared storage[1].

[1] NFS is only coherent with close-to-open which right now is not good enough 
for migration.

Regards,

Anthony Liguori

>
> [PATCH 4/5] Reopen files after migration
>
> The symptom is, when running disk stress or any intense IO operation in guest
> while migrating it causes a qcow2 corruption. We've seen this consistently on
> the daily test jobs, both for qemu and qemu-kvm. The test that triggers it is
> autotest stress test running on a VM with ping-pong background migration.
>
> The fix proposed by Juan is on our RHEL branch and such a problem does not
> happen on the RHEL branch. So, what about re-considering Juan's patch, or maybe
> work out a solution that is satisfactory for the upstream maintainers?
>
> I'll open a launchpad bug with this report.
>
> Thanks,
>
> Lucas
>