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On Mon, 2018-12-03 at 10:07 -0500, Jay Pipes wrote:
> On 12/03/2018 09:08 AM, Roman Dobosz wrote:
> > Hi,
> > 
> > We have an issue regarding live migrate old instances.
> > 
> > On our infrastructure based on Newton, we had not well named our
> > aggregation groups and we decided to completely change the naming
> > conventions. We are using extra specs/metadata in flavors/aggregates and
> > AggregateInstanceExtraSpecsFilter to select the set of hosts.
> > 
> > After changing one of the key (lets call it 'kind') of extra
> > spec/metadata to the new value, we are able to create new instances, but
> > unable to live-migrate old one. This is because of stored flavor extra
> > specs in instance_extra, which still holds the old value for the 'kind'
> > key, and make the aggregate filter fail to match the hosts.
> > 
> > In our opinion, it should be able to live-migrate such instance, since
> > only the flavor metadata has changed, while other fields doesn't (vcpus,
> > memory, disk).
> > 
> > Is it a bug? Or maybe it is possible to change the instance flavor
> > extra spec?
> 
> Not sure it's a bug, per-se... might just be something you need to 
> manually change database records for, though. Sucks, since it's hacky, 
> but not sure if it's something we should change in the API contract.
depending on what that extra spec was nova could not assume that changing
it would not impact that vms runtime or how its scheduled.  As an RFE however i 
might be worth considering if we could/show allow a resize to the same flavor so
that we can update the embeded flavor to pickup extra specs changes.

if we allowed such a resize and the live resize spec makes progess then perhaps that
woudl be a clean resolution to this usecase?
> 
> Best,
> -jay
>