live-migration fails when instance booted without specified availability_zone

[Timofey Durakov]

If instance is booted without availability-zone parameter. It's value in instances table equal NULL.
If live-migrate such instance, all hosts, even those, which belongs to another availability zone are correct.
This could cause problems with attached volumes, and whole live-migration

[Sylvain Bauza (sylvain-bauza)]

That all comes to the problem that the scheduler is bypassed when you're specifying a target host, so the AZFilter is not called.

I'm working on a blueprint for adding a check even if the target host is provided, see https://blueprints.launchpad.net/nova/+spec/check-destination-on-migrations

Leaving that bug confirmed but I think we need the blueprint I mentioned for correctly fixing the bug.

[Timofey Durakov (tdurakov)]

when instance is booted, no az info is set in db for nstance, then when we try live-migrate it. scheduler decides that every az is acceptable. We should check request specs that passed in scheduler, and if no az is provided manually calculate real az by host before filters start working

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/180438

[Sylvain Bauza (sylvain-bauza)]

As discussed on IRC, the issue you mention comes from the fact that default_schedule_zone conf flag is set to None by default.

As it's defaulted to None, then the instance has no AZ unless the user specifically asks for one, so the AZFilter doesn't care about it.

If you want to have a default AZ for each instance, please set default_schedule_zone to the default AZ you want (ideally, the same as for default_availability_zone)

[OpenStack Infra (hudson-openstack)]

Change abandoned by Timofey Durakov (<email address hidden>) on branch: master
Review: https://review.openstack.org/180438

[OpenStack Infra (hudson-openstack)]

Change abandoned by Timofey Durakov (<email address hidden>) on branch: master
Review: https://review.openstack.org/180915