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[OpenStack Infra <1718512@xxxxxxxxxxxxxxxxxx>]

Reviewed:  https://review.openstack.org/559447
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=6647f11dc1aba89f9b0e2703f236a43f31d88079
Submitter: Zuul
Branch:    master

commit 6647f11dc1aba89f9b0e2703f236a43f31d88079
Author: Matt Riedemann <mriedem.os@xxxxxxxxx>
Date:   Fri Apr 6 20:28:53 2018 -0400

    Don't persist RequestSpec.retry
    
    During a resize, the RequestSpec.flavor is updated
    to the new flavor. If the resize failed on one host
    and was rescheduled, the RequestSpec.retry is updated
    for that failed host and mistakenly persisted, which
    can affect later move operations, like if an admin
    targets one of those previously failed hosts for a
    live migration or evacuate operation.
    
    This change fixes the problem by not ever persisting
    the RequestSpec.retry field to the database, since
    retries are per-request/operation and not something
    that needs to be persisted.
    
    Alternative to this, we could reset the retry field
    in the RequestSpec.reset_forced_destinations method
    but that would be slightly overloading the meaning
    of that method, and the approach taken in this patch
    is arguably cleaner since retries shouldn't ever be
    persisted. It should be noted, however, that one
    advantage to resetting the 'retry' field in the
    RequestSpec.reset_forced_destinations method would
    be to avoid this issue for any existing DB entries
    that have this problem.
    
    The related functional regression test is updated
    to show the bug is now fixed.
    
    Change-Id: Iadbf8ec935565a6d4ccf6f36ef630ab6bf1bea5d
    Closes-Bug: #1718512


** Changed in: nova
       Status: In Progress => Fix Released

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https://bugs.launchpad.net/bugs/1718512

Title:
  migration fails if instance build failed on destination host

Status in OpenStack Compute (nova):
  Fix Released
Status in OpenStack Compute (nova) ocata series:
  Confirmed
Status in OpenStack Compute (nova) pike series:
  In Progress
Status in OpenStack Compute (nova) queens series:
  In Progress

Bug description:
  (OpenStack Nova, commit d8b30c3772, per OSA-14.2.7)

  if an instance build fails on a hypervisor the "retry" field of the
  instance's request spec is populated with which host and how many
  times it attempted to retry the build. this field remains populated
  during the life-time of the instance.

  if a live-migration for the same instance is requested, the conductor
  loads this request spec and passes it on to the scheduler. the
  scheduler will fail the migration request on RetryFilter since the
  target was already known to have failed (albeit, for the build).

  with the help of mriedem and melwitt of #openstack-nova, we determined
  that migration retries are handled separately from build retries.
  mriedem suggested a patch to ignore the retry field of the instance
  request spec during migrations. this patch allowed the failing
  migration to succeed.

  it is important to note that it may fail the migration again, however
  there is still sufficient reason to ignore the build's
  failures/retries during a migration.

  12:55 < mriedem> it does stand to reason that if this instance failed to build originally on those 2 hosts, that live migrating it there might fail too...but we don't know why it originally failed, could have been a resource claim issue at the time
  12:58 < melwitt> yeah, often it's a failed claim. and also what if that compute host is eventually replaced over the lifetime of the cluster, making it a fresh candidate for several instances that might still avoid it because they once failed to build there back when it was a different machine

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