Comment 4 for bug 1489335

Reviewed: https://review.openstack.org/187270
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=f586043fa969b9d1dcf4933aacbf615f53691093
Submitter: Jenkins
Branch: master

commit f586043fa969b9d1dcf4933aacbf615f53691093
Author: Jon Bernard <email address hidden>
Date: Mon Jun 1 14:09:30 2015 -0400

    Add support for file I/O volume migration

    This patch changes the generic volume migration logic to support
    non-attachable volumes. Non-attachable refers to volume drivers that do
    not support attachment via the typical iSCSI or similar protocols where
    a block device is made available on the host machine. Device drivers
    such as RBD make volumes available to cinder via a file handle that
    proxies read() and write() calls to the Ceph cluster.

    This patch improves the generic migration logic to determine whether a
    migration operation can proceed with dd using block device paths or file
    operations on handles returned from the os-brick connectors.

    Changes to the RBD driver are included to correctly rename the target
    volume during the completion phase of a successful migration.

    It appears there is still some work to be done for attached in-use
    volume migration for certain configurations. Successful tests were seen
    for:

      LVM to LVM (available and in-use)
      LVM to/from NFS (available and in-use)
      LVM to/from Ceph (available)
      Ceph to LVM (in-use)
      NFS to/from Ceph (available)
      Ceph to NFS (in-use)

    Failures were seen (due to Nova) for the following:

      LVM to Ceph (in-use)
      NFS to Ceph (in-use)

    (Pulled from gate, cinder can no longer pass unit tests)

    Blueprint: generic-volume-migration
    Closes-Bug: #1489335
    Closes-Bug: #1489337
    Change-Id: Iece2776fa751152f97b389ddab426e50c6f79bea