[openstack-dev] [nova] Supporting force live-migrate and force evacuate with nested allocations

Jay Pipes jaypipes at gmail.com
Tue Oct 9 19:20:05 UTC 2018

On 10/09/2018 11:04 AM, Bal√°zs Gibizer wrote:
> If you do the force flag removal in a nw microversion that also means
> (at least to me) that you should not change the behavior of the force
> flag in the old microversions.


Keep the old, buggy and unsafe behaviour for the old microversion and in 
a new microversion remove the --force flag entirely and always call GET 
/a_c, followed by a claim_resources() on the destination host.

For the old microversion behaviour, continue to do the "blind copy" of 
allocations from the source compute node provider to the destination 
compute node provider. That "blind copy" will still fail if there isn't 
capacity for the new allocations on the destination host anyway, because 
the blind copy is just issuing a POST /allocations, and that code path 
still checks capacity on the target resource providers. There isn't a 
code path in the placement API that allows a provider's inventory 
capacity to be exceeded by new allocations.


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