Target host in nova DB got updated to new compute while migration failed

[Sahid Orentino]

During live-migration if the process goes in a unpredictable situation for example if QEMU suffers an issue Nova could still consider the migration has succeeded even if not.

The VM on source node can be still registered even if stopped. In the worst scenario, the operator could start it and so two VMs running could share the same disk.

We should fix that issue, do not consider a migration to have succeeded if it was not the case. For that we should handle the return migrateToURI*

[1] http://git.openstack.org/cgit/openstack/nova/tree/nova/virt/libvirt/driver.py#n6303
[2] http://git.openstack.org/cgit/openstack/nova/tree/nova/virt/libvirt/migration.py#n223

[Daniel Berrange (berrange)]

Driving any logic off the return value of migrateToURI* is really a bad idea. When migrateToURI* fails, there are many different states the VM can be in on either the src/dst host, and the migrateToURI return status gives no useful info about which applies. Migration might even have 100% succeeded, despite migrateToURI returning an error. This is why Nova stopped looking at migrateToURI error status and switched to the job info records, to solve https://bugs.launchpad.net/nova/+bug/1414065

[Sean Dague (sdague)]

There are no currently open reviews on this bug, changing the status back to the previous state and unassigning. If there are active reviews related to this bug, please include links in comments.

[Sean Dague (sdague)]

Found open reviews for this bug in gerrit, setting to In Progress.

review: https://review.openstack.org/409261 in branch: master
review: https://review.openstack.org/409260 in branch: master

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean Dague (<email address hidden>) on branch: master
Review: https://review.openstack.org/409261
Reason: This review is > 4 weeks without comment, and is not mergable in it's current state. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[OpenStack Infra (hudson-openstack)]

Change abandoned by sahid (<email address hidden>) on branch: master
Review: https://review.openstack.org/409260

[OpenStack Infra (hudson-openstack)]

Change abandoned by sahid (<email address hidden>) on branch: master
Review: https://review.openstack.org/409261