[openstack-dev] [nova] live migration in Mitaka

Daniel P. Berrange berrange at redhat.com
Wed Oct 7 09:10:38 UTC 2015

On Tue, Oct 06, 2015 at 06:27:12PM +0100, Paul Carlton wrote:
> On 06/10/15 17:30, Chris Friesen wrote:
> >On 10/06/2015 08:11 AM, Daniel P. Berrange wrote:
> >>On Tue, Oct 06, 2015 at 02:54:21PM +0100, Paul Carlton wrote:
> >>>https://review.openstack.org/#/c/85048/ was raised to address the
> >>>migration of instances that are not running but people did not warm to
> >>>the idea of bringing a stopped/suspended instance to a paused state to
> >>>migrate it.  Is there any work in progress to get libvirt enhanced to
> >>>perform the migration of non active virtual machines?
> >>
> >>Libvirt can "migrate" the configuration of an inactive VM, but does
> >>not plan todo anything related to storage migration. OpenStack could
> >>already solve this itself by using libvirt storage pool APIs to
> >>copy storage volumes across, but the storage pool worked in Nova
> >>is stalled
> >>
> >>https://review.openstack.org/#/q/status:abandoned+project:openstack/nova+branch:master+topic:bp/use-libvirt-storage-pools,n,z
> >>
> >
> >What is the libvirt API to migrate a paused/suspended VM? Currently nova
> >uses dom.managedSave(), so it doesn't know what file libvirt used to save
> >the state.  Can libvirt migrate that file transparently?
> >
> >I had thought we might switch to virDomainSave() and then use the cold
> >migration framework, but that requires passwordless ssh.  If there's a way
> >to get libvirt to handle it internally via the storage pool API then that
> >would be better.
> >
> >Chris
> >
> >__________________________________________________________________________
> >
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> So my reading of this is the issue could be addressed in Mitaka by
> implementing
> http://specs.openstack.org/openstack/nova-specs/specs/kilo/approved/use-libvirt-storage-pools.html
> and
> https://review.openstack.org/#/c/126979/4/specs/kilo/approved/migrate-libvirt-volumes.rst
> is there any prospect of this being progressed?

The guy who started that work, Solly Ross, is no longer involved in the
Nova project. The overall idea is still sound, but the patches need more
work to get them into a state suitable for serious review & potential
merge. So it is basically waiting for someone motivated to take over
the existing patches Solly did...

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