Comment 27 for bug 1867163

Reviewed: https://review.opendev.org/c/openstack/cinder/+/760362
Committed: https://opendev.org/openstack/cinder/commit/0d1f9e9b6cb7ee1d1124f278b5df717ed96f62db
Submitter: "Zuul (22348)"
Branch: stable/queens

commit 0d1f9e9b6cb7ee1d1124f278b5df717ed96f62db
Author: Helen Walsh <email address hidden>
Date: Fri Jun 12 15:29:00 2020 +0100

    PowerMax Driver - Legacy volumes fail to live migrate

    The fix moves the legacy shared volume from the masking view
    structure in Ocata and sooner (when SMI-S was supported) to staging
    masking view(s) in Pike and later releases (U4P REST).
    In Ocata, the live migration process shared the storage group,
    containing the volume, among the different compute Nodes. In PIke,
    we changed the masking view structure to facilitate a cleaner live
    migration process where only the volume is migrated and not all the
    other volumes in the storage group. The staging storage group and
    masking views facilitate a seamless live migration operation in
    upgraded releases.

    This is not a clean backport from Rocky because of the introduction
    of multi-attach in https://review.opendev.org/c/openstack/cinder/+/556780
    so minor modifications needed to be made.

    Change-Id: I4d28d8ed2375f68eed511de5c25898362eac1def
    Closes-Bug: #1867163
    (cherry picked from commit 197e024747ca04daeb35a9eaa9f1350089211ea3)
    (cherry picked from commit 5dd1fa9a7873052e3fd87e41b960ae4b3de2136a)
    (cherry picked from commit 509ae6459cafab359b743718b2108c6d821eaf6a)
    (cherry picked from commit 91619ce3297553401c01c371690b29b68f11f17f)