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) ? Thanks On Mon, 2008-12-01 at 15:12 +0100, Chris Lalancette wrote:

Mickaël Canévet wrote:

...

Hi,

I just installed libvirt 0.5.0 on Debian Lenny with KVM 0.72 to try KVM migration support.

When I try to migrate a VM from one node to the other one, I have this error message:

libvir: error : this function is not supported by the hypervisor: virDomainMigrate

Is it really supposed to work ? Do I have to upgrade KVM to a newer version ?

Yes, it is supposed to work, but yes, you need a very, very new KVM. In particular, you need at least kvm-77, and it won't really work right until you get to kvm-79.

-- _______________________________________________________________________ Mickaël Canévet. European Molecular Biology Laboratory (EMBL) Grenoble Outstation. FRANCE _______________________________________________________________________

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. -- Chris Lalancette

Mickaël Canévet wrote:

On Tue, 2008-12-02 at 09:11 +0100, Chris Lalancette 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

Mickaël Canévet wrote: 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