Hi all, KVM block migration support in OpenStack (https://blueprints.launchpad.net/nova/+spec/kvm-block-migration) seems to be somewhat of a secret - there's almost nothing in the docs/guides (which to the contrary state that live migration is only possible with shared storage) and only a couple of mentions on list, yet it's been around since Diablo. Should this be taken to mean it's considered unstable, or just that no-one interested in documenting it understands the significance of such a feature to deployment architects? After all, decent shared storage is an expensive prospect with a pile of associated design and management overhead!
I'd be happy to contribute some documentation patches (starting with the admin guide) that cover this. But first I'd like to get some confirmation that it's here to stay, which will be significant for our own large deployment. We've tested with Essex on Ubuntu Precise and seen a bit of weird file-system behaviour, which we currently suspect might be a consequence of using ext3 in the guest. But also, there seems to be some associated lag with interactive services (e.g. active VNC session) in the guest, not yet sure how this compares to the non-block live migration case. We'd really appreciate anybody actively using this feature to speak up and comment on their mileage, especially with respect to ops. I'm slightly concerned that KVM may drop this going forward (http://www.spinics.net/lists/kvm/msg72228.html), though that would be unlikely to affect anybody deploying on Precise. -- Cheers, ~Blairo _______________________________________________ Mailing list: https://launchpad.net/~openstack Post to : openstack@lists.launchpad.net Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp
