On 16.02.2015 11:16, Daniel P. Berrange wrote: > On Mon, Feb 16, 2015 at 01:42:13PM +1100, Tony Breeds wrote: >> Hello all, >> I'm new to both openstack and libvirt so I may get some of this slightly >> wrong[1]. >> >> Here is some context form the openstack world (which at least some of you are >> aware of). There are at least 2 open bug against openstack (nova) in the area >> of block/disk migration. >> >> 1) Live migration fails when the instance has a config-drive[2] >> Here openstack(nova) fails because a drive that nova expects to be migrated >> isn't migrated. >> >> 2) libvirt live_snapshot periodically explodes on libvirt 1.2.2 in the gate[3] >> Here openstack(nova) fails because a drive that nova expects NOT to be >> migrated is migrated. >> >> To me these are essentially the same bug/issue. There is no way to communicate with >> libvirt the users expectations around block/disk mirgration. >> >> My idea so far would be to add an options element to the 'disk' XML node. >> This element could start with 3 possible states >> >> block_migration="default": Let libvirt decide >> block_migration="yes": This device should be block migrated >> block_migration="no": This device should *NOT* be block migrated >> >> The absence of this element would be treated as "default" above. >> >> This would mean that all existing domain XML would still be valid and have the >> expected behaviour and users (such as opensatck) can be explicit about deviced >> that do/do not need to be block migrated. >> >> While I'm certainly open to discussing the finer points of the implementation, >> right now I'm interested in getting a feel for is this idea generally ok? > > This doesn't really belong in the XML. The XML configs are for controlling > the guest configuration, not functional behaviour of the APIs. So we need > to fit any neccessary information into the migration API parameters instead, > or define a new migration API for it. At minimum we just want a list of > disks to be migrated. We have a migrate API that takes an array of virTypedParameter. We can use that to let users pass a list of disks to migrate. Michal -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list