[ops][nova] How to update from N to N+3 (and manage nova services that don't start because they find too old compute nodes...)

Gorka Eguileor geguileo at redhat.com
Mon Jan 10 20:05:57 UTC 2022

On 10/01, Dan Smith wrote:
> > Good to know that it is not necessary for nova to go through ALL
> > intermediate releases and perform db-sync The question is if this is
> > true for ALL openstack services (in our deployment the controller node
> > is used for all services and not only for nova)
> Actually, Sean is wrong here - we do expect you to go through each
> release on the controller, it's just that it's rare that it's actually a
> problem. We have had blocker migrations at times in the past where we
> have had to ensure that data is migrated before changing or dropping
> items of schema. We also recently did a schema compaction, which
> wouldn't tolerate moving across the releases without the (correct)
> intermediate step.
> We definitely should fix the problem related to compute records being
> old and causing the controllers to start. However, at the moment, you
> should still assume that each intermediate release needs to be db-sync'd
> unless you've tested that a particular source and target release
> works. I expect the same requirement for most other projects.
> --Dan


Unrelated to this Nova issue, but related to why intermediate releases
cannot be skipped in OpenStack, the Cinder project requires that the db
sync and the online data migrations are run on each intermediate

You may be lucky and everything may run fine, but it might as well blow
up in your face and lose database data.


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