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

Daniel P. Berrange berrange at redhat.com
Thu Oct 8 08:57:44 UTC 2015

On Wed, Oct 07, 2015 at 03:54:29PM -0600, Chris Friesen wrote:
> On 10/07/2015 03:14 AM, Daniel P. Berrange wrote:
> >For suspended instances, the scenario is really the same as with completely
> >offline instances. The only extra step is that you need to migrate the saved
> >image state file, as well as the disk images. This is trivial once you have
> >done the code for migrating disk images offline, since its "just one more file"
> >to care about.  Officially apps aren't supposed to know where libvirt keeps
> >the managed save files, but I think it is fine for Nova to peek behind the
> >scenes to get them. Alternatively I'd be happy to see an API added to libvirt
> >to allow the managed save files to be uploaded & downloaded via a libvirt
> >virStreamPtr object, in the same way we provide APIs to  upload & download
> >disk volumes. This would avoid the need to know explicitly about the file
> >location for the managed save image.
> Assuming we were using libvirt with the storage pools API could we currently
> (with existing libvirt) migrate domains that have been suspended with
> virDomainSave()?  Or is the only current option to have nova move the file
> over using passwordless access?

If you used virDomainSave() instead of virDomainManagedSave() then you control
the file location, so you could create a directory based storage pool and
save the state into that directory, at which point you can use the storag
pool APIs to upload/download that data.

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