[openstack-dev] [nova] About doing the migration claim with Placement API

Alex Xu soulxu at gmail.com
Wed Nov 2 11:26:30 UTC 2016


2016-11-02 16:26 GMT+08:00 Sylvain Bauza <sbauza at redhat.com>:

>
>
> Le 01/11/2016 15:14, Alex Xu a écrit :
>
> Currently we only update the resource usage with Placement API in the
> instance claim and the available resource update periodic task. But there
> is no claim for migration with placement API yet. This works is tracked by
> https://bugs.launchpad.net/nova/+bug/1621709. In newton, we only fix one
> bit which make the resource update periodic task works correctly, then it
> will auto-heal everything. For the migration claim part, that isn't the
> goal for newton release.
>
>
> To be clear, there are two distinct points :
> #1 there are MoveClaim objects that are synchronously made on resize (and
> cold-migrate) and rebuild (and evacuate), but there is no claim done by the
> live-migration path.
> There is a long-standing bugfix https://review.openstack.org/#/c/244489/
> that's been tracked by https://bugs.launchpad.net/nova/+bug/1289064
>

Yea, thanks for the info. I say `migration claim` is more about the move
claim. Maybe I should say the move claim.

>
>
> #2 all those claim operations don't trigger an allocation request to the
> placement API, while the regular boot operation does (hence your bug
> report).
>

Yes, except the booting new instance, other claims won't trigger allocation
request to the placement API.


>
>
>
>
> So the first question is do we want to fix it in this release? If the
> answer is yes, there have a concern need to discuss.
>
>
> I'd appreciate if we could merge first #1 before #2 because the placement
> API decisions could be wrong if we decide to only allocate for certain move
> operations.
>

Sorry, I didn't get you, what is 'the placement API decisions' pointed to?


>
>
> In order to implement the drop of migration claim, the RT needs to remove
> allocation records on the specific RP(on the source/destination compute
> node). But there isn't any API can do that. The API about remove allocation
> records is 'DELETE /allocations/{consumer_uuid}', but it will delete all
> the allocation records for the consumer. So the initial fix(
> https://review.openstack.org/#/c/369172/) adds new API 'DELETE
> /resource_providers/{rp_uuid}/allocations/{consumer_id}'. But Chris Dent
> pointed out this against the original design. All the allocations for the
> specific consumer only can be dropped together.
>
> There also have suggestion from Andrew, we can update all the allocation
> records for the consumer each time. That means the RT will build the
> original allocation records and new allocation records for the claim
> together, and put into one API. That API should be 'PUT
> /allocations/{consumer_uuid}'. Unfortunately that API doesn't replace all
> the allocation records for the consumer, it always amends the new
> allocation records for the consumer.
>
> So which directly we should go at here?
>
> Thanks
> Alex
>
>
>
>
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