Comment 3 for bug 1497253

Reviewed: https://review.openstack.org/226977
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=d8d2f02f3014e8d7e0ef9a61723f5a10f050cc81
Submitter: Jenkins
Branch: master

commit d8d2f02f3014e8d7e0ef9a61723f5a10f050cc81
Author: Matt Riedemann <email address hidden>
Date: Wed Sep 23 13:21:06 2015 -0700

    Deprecate cinder.cross_az_attach option

    Introduced in 1504cbc5d4a27695fa663f0b0f3f7b48745bdb45 in Grizzly, the
    use cases around this option are unclear but there have been several
    bugs related to it.

    For example, 6060888b58db42eea826939852838f9e1c204d2c changed boot from
    volume to pass the server instance availability zone to cinder when
    creating the volume. However, if that same AZ does not exist in Cinder,
    the volume create request will fail - which is bug 1496235.

    Cinder works around this with b85d2812a8256ff82934d150dbc4909e041d8b31
    using a config option to allow falling back to a default Cinder AZ if
    the one requested does not exist. By default this fallback is disabled
    though.

    It also sounds like availability zones in Cinder were an artifact from
    when Cinder was split out from the nova-volume service, but Cinder AZ
    use cases are also unclear. And it's also unclear what the relationship
    is between AZs in Nova and Cinder.

    So given the problems here and the lack of a clear use case to justify
    having this configuration option in tree, along with it's added
    complexity, deprecate the option for removal.

    Related-Bug: #1496235
    Related-Bug: #1380780
    Related-Bug: #1489575
    Related-Bug: #1497253

    Change-Id: I52cd3d8867d3b35f5caba377302bfc52c112f1d6