Comment 8 for bug 1203152

Reviewed: https://review.openstack.org/50984
Committed: http://github.com/openstack/cinder/commit/8a2a3d691fa54c07d14b3e32558641f43b69c040
Submitter: Jenkins
Branch: milestone-proposed

commit 8a2a3d691fa54c07d14b3e32558641f43b69c040
Author: Alan Jiang <email address hidden>
Date: Thu Oct 3 17:03:09 2013 -0500

    long flashcopy operation may block volume service

    Storwize family uses flashcopy for snapshot or volume clone. The
    volume delete has to wait until flashcopy finishes or errors out.
    The _delete_vdisk() will poll volume FlashCopy status in a loop.
    This may block volume serivce heartheat since it is in the same
    . The solution is to use openstack FixedIntervalLoopingCall
    to run the FlashCopy status poll in a timer thread.

    The cinder volume mananger will resume delete operation for those
    volumes that are in the deleting state during volume service startup.
    Since Storwize volume delete may wait for a long time, this can cause
    volume service to have long delay before it becomes available.
    A greenpool is used to offload those volume delete operations.

    Change-Id: Ie01a441a327e1e318fa8da0040ae130731b7a686
    Closes-Bug: #1203152
    (cherry picked from commit 7aa4f65a8c17aa037deff0f5b534ed694c17e62a)