Comment 12 for bug 1813789

Reviewed: https://review.opendev.org/713961
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=91d410b92f86524dffb781c7a49ecb3ec8ac8a56
Submitter: Zuul
Branch: stable/train

commit 91d410b92f86524dffb781c7a49ecb3ec8ac8a56
Author: Lee Yarwood <email address hidden>
Date: Wed Mar 18 15:17:27 2020 +0000

    nova-live-migration: Ensure subnode is fenced during evacuation testing

    As stated in the forced-down API [1]:

    > Setting a service forced down without completely fencing it will
    > likely result in the corruption of VMs on that host.

    Previously only the libvirtd service was stopped on the subnode prior to
    calling this API, allowing n-cpu, q-agt and the underlying guest domains
    to continue running on the host.

    This change now ensures all devstack services are stopped on the subnode
    and all active domains destroyed.

    It is hoped that this will resolve bug #1813789 where evacuations have
    timed out due to VIF plugging issues on the new destination host.

    [1] https://docs.openstack.org/api-ref/compute/?expanded=update-forced-down-detail#update-forced-down

    NOTE(lyarwood): The following change is squashed here to allow both to
    pass the gate without encoutering additional failures.

    nova-live-migration: Only stop n-cpu and q-agt during evacuation testing

    I8af2ad741ca08c3d88efb9aa817c4d1470491a23 started to correctly fence the
    subnode ahead of evacuation testing but missed that c-vol and g-api
    where also running on the host. As a result the BFV evacuation test will
    fail if the volume being used is created on the c-vol backend hosted on
    the subnode.

    This change now avoids this by limiting the services stopped ahead of
    the evacuation on the subnode to n-cpu and q-agt.

    Change-Id: Ia7c317e373e4037495d379d06eda19a71412d409
    Closes-Bug: #1868234
    (cherry picked from commit 1e16b3184d4e298c454ede7c56040f6d70276a0c)

    Related-Bug: #1813789
    Change-Id: I8af2ad741ca08c3d88efb9aa817c4d1470491a23
    (cherry picked from commit b097959c1cbc9af1d90c7502286bc3e20972201f)