NetApp ESeries driver: warn if 'use_multipath_for_image_xfer' is not set to True

[Tom Barron]

ESeries filers require appropriate multipath/DMMP configuration on the host running cinder volume process for volume attach and image transfers to work reliably and efficiently, and the cinder.conf option 'use_multipath_for_image_xfer' should be set to True.

Here we will commit a fix to log a warning on driver startup if Eseries backend is being used and 'use_multipath_for_image_xfer' is not set to True.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/125654

[Huang Zhiteng (zhiteng-huang)]

Is this config option also useful to other NetApp model? If a configuration option is required to be always true, the driver should do it (setting it to be True no matter what) instead of log a warning.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/125654
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=933a7c01ffa78810b283aa3c3b32d75e4c4504bb
Submitter: Jenkins
Branch: master

commit 933a7c01ffa78810b283aa3c3b32d75e4c4504bb
Author: Tom Barron <email address hidden>
Date: Tue Sep 23 18:05:40 2014 -0400

    Eseries warn if multipath is not set for img xfer

    Warn at driver startup if the configuration option
    "use_multipath_for_image_xfer" has not been set to "True". Eseries filers
    require appropriate multipath/DMMP configuration on the host running the
    cinder volume process for image transfers to work reliably.

    Change-Id: Ib79a23a5a9527b254f155a9f4ea022d4387a4a13
    Closes-Bug: #1376349