Create CG from cgsnapshot failed due to error 'LUN is migrating' with VNX driver

[Tina Tang]

When create CG from cgsnapshot, occasionally we failed with below error:

'Cannot put the LUN in the consistency group because the LUN is migrating. Please wait until migration completes and retry the operation. LUN: 63876\\n\\n'

Logs:
2015-09-16 02:51:52.875 124906 DEBUG cinder.volume.drivers.emc.emc_vnx_cli [-] Migration of LUN 63876 is finished. migration_is_ready /opt/stack/cinder/cinder/volume/drivers/emc/emc_vnx_cli.py:10292015-09-16 02:52:00.963 ERROR oslo_messaging.rpc.dispatcher [req-ade8638d-ce49-495e-b0d1-dc963b109267 None] Exception during message handling: EMC VNX Cinder Driver CLI exception: ('-np', 'snap', '-group', '-create', '-name', '8298b69d-936f-4589-b897-f653c3e5ed0b', '-allowSnapAutoDelete', 'no', '-res', u'63876') (Return Code: 40) (Output: [u'Cannot put the LUN in the consistency group because the LUN is migrating. Please wait until migration completes and retry the operation. LUN: 63876\\n\\n']).2015-09-16 02:52:00.963 124906 ERROR oslo_messaging.rpc.dispatcher EMCVnxCLICmdError: EMC VNX Cinder Driver CLI exception: ('-np', 'snap', '-group', '-create', '-name', '8298b69d-936f-4589-b897-f653c3e5ed0b', '-allowSnapAutoDelete', 'no', '-res', u'63876') (Return Code: 40) (Output: [u'Cannot put the LUN in the consistency group because the LUN is migrating. Please wait until migration completes and retry the operation. LUN: 63876\\n\\n']).

Per the log, the migration is actually finished, but the driver didn't get the updated status so that add the LUN into CG failed.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/224401

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/224401
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=9c4c994b952d7af5252c88e9486424033fa95d1b
Submitter: Jenkins
Branch: master

commit 9c4c994b952d7af5252c88e9486424033fa95d1b
Author: Tina <email address hidden>
Date: Tue Sep 15 23:38:03 2015 -0400

    Fixing create CG from Cgsnapshot bug in VNX driver

    When creating a consistency group from a cgsnapshot, VNX driver
    didn't force a poll to the VNX system. This caused the creation
    to fail because the out-of-date status was returned. This patch
    forces a poll to the VNX system to get rid of this issue.

    Change-Id: I710bd0ac2a6049a79fce0d552ad8fba2c9fbde67
    Closes-Bug: #1496660