[libvirt] libvirt 0.5.0 and KVM migration

[Chris Lalancette]

Mickaël Canévet wrote:
> On Tue, 2008-12-02 at 09:11 +0100, Chris Lalancette wrote:
>> Mickaël Canévet wrote:
>>> Thanks for your quick answer.
>>>
>>> I forgot to restart libvirt on one node.
>>>
>>> Now I have an other error message:
>>>
>>> libvir: QEMU error : operation failed: failed to start listening VM
>>>
>>> Is there any kernel limitation also ? will it work with my distro 2.6.26
>>> kernel with kvm-79 userspace component or do I have to have kvm-79
>>> kernel module also, or even kernel then 2.6.26 ?
>>>
>>> In other (debian) words, will an "apt-get update kvm -t
>>> experimental" (which provides kvm-79) be enough on my lenny (I would
>>> like to limit unstable or experimental packages) ?
>> Just an updated kvm-79 userspace *should* work; for instance, in oVirt, we are
>> running a kvm-79 userspace equivalent on a 2.6.27 kernel, which is slightly
>> older.  In general, a new kvm userspace should work on an older kernel, but it
>> is not a heavily tested configuration, so your results might vary.
>>
> OK,
> 
> I updated both userspace and kernel module to kvm-79.
> Now migration begins, but:
> - On the source node, the command does not returns and an strace shows
> that it does nothing (wait4(9709, )
> - On the destination node, I can connect threw the VNC display, but
> there seams to have a strange issue with I/O (lot of messages on
> console; sd 0:0:0:0: rejecting I/O to offline device). FYI my VM disk is
> a DRBD over LVM as dual primary.
> - From another PC, I lose a few pings during migration.
> 
> Are my I/0 errors comes from my backend storage (DRBD) ?

Probably, it's hard to say without knowing more about your setup (and I don't
really know anything about DRBD, sorry).  In any case, you are probably out of
the realm of libvirt at this point; libvirtd has done the right thing, I think,
so any other errors are probably down to KVM itself.  It might be best to test
the same setup by hand (that is, not use libvirt, but execute the qemu-kvm
binary directly).  If you are still having problems with that, then you can
debug kvm directly and/or mail qemu-devel and kvm-devel.

-- 
Chris Lalancette