Comment 2 for bug 1078594

Reviewed: https://review.openstack.org/16134
Committed: http://github.com/openstack/nova/commit/c2de33a0a2132774dc295861cef138ec24bb0cf9
Submitter: Jenkins
Branch: master

commit c2de33a0a2132774dc295861cef138ec24bb0cf9
Author: Michael Still <email address hidden>
Date: Wed Nov 14 18:37:04 2012 +1100

    Detect shared storage; handle base cleanup better.

    If base image storage is shared, we need to care about remote
    instances when we clean up. This patch "learns" which storage is
    shared, and then decides what base images are in use anywhere
    on the set of compute nodes which share that base storage.

    This is complicated because shared instance storage doesn't have
    to be per-cluster. It could for example be per rack. We need to
    handle that properly.

    This should resolve bug 1078594.

    Change-Id: I36d0d6e965b114bb68c8f7b7fd43f8e96b2dd8f5