---
upgrade:
  - |
    Starting in Ocata, there is a behavior change where aggregate-based
    overcommit ratios will no longer be honored during scheduling for the
    FilterScheduler. Instead, overcommit values must be set on a
    per-compute-node basis in the Nova configuration files.

    If you have been relying on per-aggregate overcommit, during your upgrade,
    you must change to using per-compute-node overcommit ratios in order for
    your scheduling behavior to stay consistent. Otherwise, you may notice
    increased NoValidHost scheduling failures as the aggregate-based overcommit
    is no longer being considered.

    You can safely remove the AggregateCoreFilter, AggregateRamFilter, and
    AggregateDiskFilter from your ``[filter_scheduler]enabled_filters`` and you
    do not need to replace them with any other core/ram/disk filters. The
    placement query in the FilterScheduler takes care of the core/ram/disk
    filtering, so CoreFilter, RamFilter, and DiskFilter are redundant.

    Please see the mailing list thread for more information:
    http://lists.openstack.org/pipermail/openstack-operators/2018-January/014748.html
