On 28.11.2012 14:00, Jiri Denemark wrote: > On Wed, Nov 28, 2012 at 10:31:54 +0800, li guang wrote: >> 在 2012-11-27二的 16:42 -0500，Eric Blake写道： >>>> This patch set re-implements migration with storage for enough new >>>> qemu. >>> >>> How does this series interact with Li Guang's efforts to add offline >>> migration? In particular, >>> >>>> 1) src -> dest: (QEMU_MIGRATION_PHASE_BEGIN3 -> >>>> QEMU_MIGRATION_PHASE_PREPARE) >>>> <nbd> >>>> <disk src='/var/lib/libvirt/images/f17.img' >>>> size='17179869184'/> >>>> </nbd> >>> >>> Both sets of patches need to pass size information across in the >>> cookies; so is tying it to <nbd> appropriate, or should we be >>> rethinking this XML to be shared between both patches? >> >> actually, I think 'src' is unnecessary, for 'def->disks[i]->src' > > 'src' is not only unnecessary it's actually totally useless since we can't > rely on it. In case a domain is migrated to a host with pre-migration hook > installed, the hook is allowed to modify parts of the XML that are not visible > to the domain. And disk source is one of them. (The same applies for > specifying the XML to be used on destination directly to virDomainMigrate* > APIs.) In other words, disk source on destination does not have to match the > path on source host. > > Jirka > Oh, right. Then we can't rely on disk ordering neither (well, for now we can because of our code being dumb-enough; but if we change it ...). I should have used device-id instead as it is the only thing that will not change. However, if it ever will - we are gonna need a mapping anyway, so we can map these device-ids then. So the migration cookie should look like this: <nbd> <disk id="drive-virtio-disk0" size="123456"/> ... </nbd> Although, I am not sure whether to include the QEMU_DRIVE_HOST_PREFIX (="drive-") or not. Michal -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list