[Openstack] [nova] Live Migration + Ephemeral disk impossible with qcow2 format

Jean-Daniel BUSSY silversurfer972 at gmail.com
Thu Jul 12 16:01:38 UTC 2012


Hi all,

I noticed a bug in Multiple OpenStack Clusters that prevent instances with
ephemeral disk to be migrated when qcow2 format is used.
The bug has need fixed here
<https://bugs.launchpad.net/nova/+bug/977007>but the fix has been
committed to the head branch for Folsom.
https://github.com/openstack/nova/commit/ee705d048418d63667136cad3951655178861d46

Live migration is a very important feature to production clouds as it
allows maintenance with 0 downtime. Even is ephemeral disk is not a best
practice, the fact that it is included in defaults profile make it more
relevant as soon-to-be-fixed bug.

I would like to know if it is planned to have the bug fixed also on Essex
branch.
Then a bug fix upgrade in ubuntu 12.04 OpenStack repository would be the
best outcome.
I would be unfortunate to have this bug on Essex with users forced to patch
between each package upgrade.

To manually fix the bug:
vim +2168 /usr/lib/python2.7/dist-packages/nova/virt/libvirt/connection.py
Change
                     size=info['disk_size'])
With
                    size=info['virt_disk_size'])

Testing works fine while migration is impossible on
version 2012.1+stable~20120612-3ee026e-0ubuntu1.2 on ubuntu 12.04

Short version:
This bug prevent live migration with ephemeral images with qcow2 images and
needs to be ported to essex asap.

Cheers,

*BUSSY Jean-Daniel*
Computer Engineer | CyberAgent
Mobile: +81 090-3317-1337
Email: silversurfer972 at gmail.com
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