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Dear operators,

do you have experience of using nova's option cross_az_attach with False
value?

Current behavior is that if cross_az_attach option is set to false, nova
should ensure cinder and nova AZ's are matching and create both volume
and instance in the same availability zone. So far, so good.

But there's potential corner case, when user is trying to create the
instance (with new volume), but does not explicitly choose any AZ. In
such case, the instance and volume may be created in different zones
(this is actually https://bugs.launchpad.net/nova/+bug/1497253).

My proposal is to try to cover this case by small change in nova
code that would decide which AZ should be used before it asks cinder to
create the volume. This is the point of
https://review.openstack.org/#/c/225119/. So even if AZ would not be
provided, having cross_az_attach set to false should mean that both
instance and volume have the same availability zone.

What do you think, does it change the way you expect it to work? For
better or worse?

Jiri
-- 
Jiri Suchomel

SUSE LINUX, s.r.o., http://www.suse.cz