[libvirt] Support to transfer OVSDB:Interface stats during Live Migration

[Laine Stump]

On 07/26/2012 09:40 PM, kiran Chunduri wrote:
> Hi,
> I was experimenting 'live migration' with libvirt (using virsh) and
> observed that post migration the Interface stats in 'OVSDB:Interface'
> table are not transferred.

I'm assuming that the "OVS" part of this is openvswitch?

> Only the values in 'external_ids'  column seem to be synced up. The
> libvirt version I'm using is 0.9.11.3. The virsh command used for
> migration is: 'virsh migrate --live fc17-vm
> qemu+ssh://10.23.167.219/system <http://10.23.167.219/system>'
>
> Is this the right behavior (or) Have I missed out on some option?

I don't know if it's "right", but moving state that's outside of the
guest itself is outside the scope of migration, at least for now.

>  
> Can some one please guide on the approach and the source files to look
> at If i need to add this support?
>

I don't really have a good idea about that. Could the information
related to a given guest interface be easily represented in XML within
the <interface> section of the guest's domain XML (which is the only
thing aside from an image of the guest's memory, and state of the
guest's emulated devices, that is transferred during a migration)? If
that's the case, maybe the openvswitch support in libvirt could be
extended to, for example, recognize some extra stuff inside of the
<virtualport type='openvswitch'> element when resuming a paused (due to
migration or save) guest, and use that data to populate the db.