[openstack-dev] [OpenStack-Dev][Nova][VMWare] Enable live migration with one nova compute

John Garbutt john at johngarbutt.com
Mon Mar 31 13:02:28 UTC 2014

On 31 March 2014 10:11, Jay Lau <jay.lau.513 at gmail.com> wrote:
> Hi,
> Currently with VMWare VCDriver, one nova compute can manage multiple
> clusters/RPs, this caused cluster admin cannot do live migration between
> clusters/PRs if those clusters/PRs managed by one nova compute as the
> current live migration logic request at least two nova computes.
> A bug [1] was also filed to trace VMWare live migration issue.
> I'm now trying the following solution to see if it is acceptable for a fix,
> the fix wants enable live migration with one nova compute:
> 1) When live migration check if host are same, check both host and node for
> the VM instance.
> 2) When nova scheduler select destination for live migration, the live
> migration task should put (host, node) to attempted hosts.
> 3) Nova scheduler needs to be enhanced to support ignored_nodes.
> 4) nova compute need to be enhanced to check host and node when doing live
> migration.
> I also uploaded a WIP patch [2] for you to review the idea of the fix and
> hope can get some comments from you.
> [1] https://bugs.launchpad.net/nova/+bug/1192192
> [2] https://review.openstack.org/#/c/84085

Long term, finding a way to unify how cells and the VMware driver
manages multiple hosts, seems like the best way forward. It would be a
shame for this API to be different between cells and VMware, although
right now, that might not work too well :(

A better short term fix, might be to allow you to specify the same
host as the instance, and the scheduling of the node could be
delegated to the VMware driver, which might just delegate that to
vCenter. I assume we still need some way to specify the node, and I
can't immediately think of a good way forward.

I feel this should really be treated as a blueprint, and go through
the new blueprint review process. That should help decide the right
approach to take.


More information about the OpenStack-dev mailing list