Comment 14 for bug 1715569

Reviewed: https://review.openstack.org/541904
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=6b753f0b5ea734432d2f45fb11884ea1b110ed77
Submitter: Zuul
Branch: stable/ocata

commit 6b753f0b5ea734432d2f45fb11884ea1b110ed77
Author: Mike Lowe <email address hidden>
Date: Mon Nov 6 11:06:46 2017 -0500

    live-mig: keep disk device address same

    During live migration disk devices are updated with the latest
    block device mapping information for volumes. Previously this
    relied on libvirt to assign addresses in order after the already
    assigned devices like the root disk had been accounted for. In
    the latest libvirt the unassigned devices are allocated first which
    makes the root disk address double allocated causing the migration to
    fail. A running instance should never have the hardware addresses
    of its disks changed mid flight. While disk address changes during
    live migration produce fatal errors for the operator it would likely
    cause errors inside the instance and unexpected behavior if the device
    addresses change during cold migrationt review. With this disk addresses are no
    longer updated with block device mapping information while every
    other element of the disk definition for a volume is updated.

    Closes-Bug: 1715569

    Change-Id: I17af9848f4c0edcbcb101b30e45ca4afa93dcdbb
    (cherry picked from commit b196857f04e41dde294eaacc2c1a991807ecc829)