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[Mark Doffman <mjdoffma@xxxxxxxxxx>]

Public bug reported:

When migrating instances should not have affinity with themselves.

This is most clearly seen with hard anti-affinity as an instance
attempting to migrate to the same host would be unable to do so due to
the presence of 'itself' on the host. (See bug #1558532).

In the soft-affinity case the consequences are not so dire, but can lead
to incorrect weights being calculated. This is due to the fact that the
soft affinity weigher counts the instance that is being migrated when
looking at the number of instances from the group on a host.

See:
https://github.com/openstack/nova/blob/master/nova/scheduler/weights/affinity.py#L49

** Affects: nova
     Importance: Low
     Assignee: Mark Doffman (mjdoffma)
         Status: New


** Tags: scheduler

** Changed in: nova
   Importance: Undecided => Low

** Changed in: nova
     Assignee: (unassigned) => Mark Doffman (mjdoffma)

** Tags added: scheduler

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https://bugs.launchpad.net/bugs/1564559

Title:
  Instances should not have soft-affinity with themselves.

Status in OpenStack Compute (nova):
  New

Bug description:
  When migrating instances should not have affinity with themselves.

  This is most clearly seen with hard anti-affinity as an instance
  attempting to migrate to the same host would be unable to do so due to
  the presence of 'itself' on the host. (See bug #1558532).

  In the soft-affinity case the consequences are not so dire, but can
  lead to incorrect weights being calculated. This is due to the fact
  that the soft affinity weigher counts the instance that is being
  migrated when looking at the number of instances from the group on a
  host.

  See:
  https://github.com/openstack/nova/blob/master/nova/scheduler/weights/affinity.py#L49

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