migration fails with virtio-blk

migration fails with virtio-blk

[Michael Tokarev]

Apparently there's an issue with migration when
virtio-blk is in use at the time migration occurs.

See Debian bug #580649 for details:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=580649

In short: 2.6.26 (guest) + 0.12.3 + virtio-blk fails.
2.6.32 guest works, 0.11 works, non-virtio-blk works.

Debian qemu-kvm is compiled without --enable-iothread -
JFYI.

The bugreport contains a backtrace taken from guest.

Now, one can say it's a bug in 2.6.26 kernel, which
is quite old.  But the problem does not occur with
qemu-kvm-0.11, so it might be treated as a regression
instead.

Thanks!

/mjt

Re: migration fails with virtio-blk

[Michael Tokarev]

10.05.2010 13:49, Michael Tokarev пишет:
> Apparently there's an issue with migration when
> virtio-blk is in use at the time migration occurs.
>
> See Debian bug #580649 for details:
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=580649
>
> In short: 2.6.26 (guest) + 0.12.3 + virtio-blk fails.
> 2.6.32 guest works, 0.11 works, non-virtio-blk works.

It looks like a problem reported on qemu-devel
list should fix the issue here:
http://marc.info/?l=qemu-devel&m=127350821419989

Testing...  It wont be fast because I want to hear
from the OP.

Thanks!

/mjt

Re: migration fails with virtio-blk

[Anthony Liguori]

On 05/10/2010 01:34 PM, Michael Tokarev wrote:
> 10.05.2010 13:49, Michael Tokarev пишет:
>> Apparently there's an issue with migration when
>> virtio-blk is in use at the time migration occurs.
>>
>> See Debian bug #580649 for details:
>> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=580649
>>
>> In short: 2.6.26 (guest) + 0.12.3 + virtio-blk fails.
>> 2.6.32 guest works, 0.11 works, non-virtio-blk works.
>
> It looks like a problem reported on qemu-devel
> list should fix the issue here:
> http://marc.info/?l=qemu-devel&m=127350821419989

Can't be, that's a vhost patch and 0.12.3 doesn't support vhost.

Regards,

Anthony Liguori

> Testing...  It wont be fast because I want to hear
> from the OP.
>
> Thanks!
>
> /mjt
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Re: migration fails with virtio-blk

[Michael Tokarev]

10.05.2010 22:38, Anthony Liguori wrote:
> On 05/10/2010 01:34 PM, Michael Tokarev wrote:
>>> In short: 2.6.26 (guest) + 0.12.3 + virtio-blk fails.
>>> 2.6.32 guest works, 0.11 works, non-virtio-blk works.
>>
>> It looks like a problem reported on qemu-devel
>> list should fix the issue here:
>> http://marc.info/?l=qemu-devel&m=127350821419989
>
> Can't be, that's a vhost patch and 0.12.3 doesn't support vhost.

Well, that was really close. qemu-kvm-0.12 has the
following code in that place:

      vdev->features = features;

the patch mentioned has this:

+    if (vdev->set_features)
+        vdev->set_features(vdev, features);

so basically kvm had the same code here,
just not wrapped into a function ;)

And sure thing you're right, it does not help any. :)

Thanks!

/mjt