reduce VM network down time during live (block) migration

[Abhishek Kekane]

It appears that during live migration, for certain duration network is unavailable and there is a scope to reduce the network downtime.

Please refer http://paste.openstack.org/show/69718/ to check the packet loss during live migration.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/78165

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/78165
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=478f447070e2aa11ac14d419ae283e6bb9edeeb3
Submitter: Jenkins
Branch: master

commit 478f447070e2aa11ac14d419ae283e6bb9edeeb3
Author: abhishek-kekane <email address hidden>
Date: Wed Feb 26 05:03:23 2014 -0800

    reduce network down time during live-migration

    Called unplug_vifs() method before post_live_migration_to_destination call
    because floating ip address will not work until the vifs are unplugged
    from the source compute node.

    Added new method post_live_migration_at_source in virt driver and
    implemented it in libvirt driver to unplug the vifs at source. Other
    drivers will raise NotImplementedError.
    Added new keyword argument destroy_vifs to cleanup() method to verify
    if unplug_vifs() is already called then do not call it again.

    Closes-Bug: #1284996
    Change-Id: Ida3ed3bef77239e5a0fdbf8866e8a4421d4f8222