Hi Eric, so I will try to downgrade libvirt in the source host back to the 0.9.8 version. To completely remove libvirt is enough to run the apt-get command with the purge option?

Same thing also for the qemu packet?

Thanks
Daniele


2013/5/7 Eric Blake <eblake@redhat.com>
On 05/07/2013 10:58 AM, Daniele wrote:
> Thanks for your answer
>
>>> The live wide migration from A to B completes successfully, instead I
>> can't
>>> achieve the reverse path, from B to A (and that is right what I am
>>> interested to). To perform the migration I run this command in virsh:
>> *"migrate
>>> --live --verbose uno qemu+ssh://root@ip.address/system"*
>>

> In the source host there is libvirtd 0.9.12, while in the destination host
> there is a modified version of the 0.9.8 (that I can't change).

There's your problem.  In general, migration is backwards-compatible
(old going to new should work; if it doesn't, that's a bug we are
prepared to fix), but not forwards-compatible (there's no way we can
ever commit to guaranteeing that new->old will work in all scenarios).
Your best bet for successful migration is to have the same version of
software on both sides of the equation, or to be prepared for only
old->new to work.  Your failure appears to be because you are trying
new->old.

> Nothing interesting in the source uno.log, but I wasn't checking in the
> destination host log. These are its last lines:
> *savevm: unsupported version 3 for 'i8254' v2*
> *load of migration failed*
> *2013-05-07 16:27:59.682+0000: shutting down*
>
> I'm also checking the libvirtd.log in the destination host (that i didn't
> look before) and it seems interesting. It reports this error:
> *2013-05-07 16:27:59.682+0000: 16651: error : qemuMonitorIO:560 : internal
> error End of file from monitor*
> *Caught Segmentation violation dumping internal log buffer:*

Yep, when migrating from new to old qemu, the new qemu was sending stuff
the old one choked on.

--
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org