Comment 23 for bug 1787910

Reviewed: https://review.openstack.org/596502
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=243ba8513097ca715af738422a9e1249c6a7a1f0
Submitter: Zuul
Branch: master

commit 243ba8513097ca715af738422a9e1249c6a7a1f0
Author: Matt Riedemann <email address hidden>
Date: Fri Aug 24 19:10:08 2018 -0400

    Deprecate Core/Ram/DiskFilter

    The time has come.

    These filters haven't been necessary since Ocata [1]
    when the filter scheduler started using placement
    to filter on VCPU, DISK_GB and MEMORY_MB. The
    only reason to use them with any in-tree scheduler
    drivers is if using the CachingScheduler which doesn't
    use placement, but the CachingScheduler itself has
    been deprecated since Pike [2]. Furthermore, as of
    change [3] in Stein, the ironic driver no longer
    reports vcpu/ram/disk inventory for ironic nodes
    which will make these filters filter out ironic nodes
    thinking they don't have any inventory. Also, as
    noted in [4], the DiskFilter does not account for
    volume-backed instances and may incorrectly filter
    out a host based on disk inventory when it would
    otherwise be OK if the instance is not using local
    disk.

    The related aggregate filters are left intact for
    now, see blueprint placement-aggregate-allocation-ratios.

    [1] Ie12acb76ec5affba536c3c45fbb6de35d64aea1b
    [2] Ia7ff98ff28b7265058845e46b277317a2bfc96d2
    [3] If2b8c1a76d7dbabbac7bb359c9e572cfed510800
    [4] I9c2111f7377df65c1fc3c72323f85483b3295989

    Change-Id: Id62136d293da55e4bb639635ea5421a33b6c3ea2
    Related-Bug: #1787910