Comment 22 for bug 1382440

Reviewed: https://review.openstack.org/144064
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=4c1f28a0f467d749ebf406f970b3cea4888ff1b0
Submitter: Jenkins
Branch: stable/juno

commit 4c1f28a0f467d749ebf406f970b3cea4888ff1b0
Author: Hiroyuki Eguchi <email address hidden>
Date: Thu Nov 20 10:41:36 2014 +0900

    Fix connecting unnecessary iSCSI sessions issue

    In Icehouse with "iscsi_use_multipath=true", attaching a multipath
    iSCSI volume may create unnecessary iSCSI sessions.

    The iscsiadm discovery command in connect_volume() returns all of the
    targets in the Cinder node, not just the ones related to the multipath
    volume which is specified by iqn. If the storage has many targets,
    connecting to all these volumes will also result in many unnecessary
    connections.

    There are two types of iSCSI multipath devices. One which shares
    the same iqn between multiple portals, and the other which use
    different iqns on different portals. connect_volume() needs to
    identify the type by checking iscsiadm the output if the iqn is
    used by multiple portals.

    This patch changes the behavior of attaching volume:

       1. Identify the type by checking the iscsiadm output.
       2. Connect to the correct targets by connect_to_iscsi_portal().

    Closes-Bug: #1382440

    (cherry picked from commit fb0de106f2f15604750bafc318ba06c41070cc35)

    Conflicts:
            nova/tests/unit/virt/libvirt/test_volume.py

    Change-Id: I488ad0c09bf26a609e27d67b9ef60b65bb45e0ad