[openstack-dev] [nova][libvirt] RFC: ensuring live migration ends

Daniel P. Berrange berrange at redhat.com
Mon Feb 2 20:26:05 UTC 2015


On Mon, Feb 02, 2015 at 01:21:31PM -0500, Andrew Laski wrote:
> 
> On 02/02/2015 11:26 AM, Daniel P. Berrange wrote:
> >On Mon, Feb 02, 2015 at 11:19:45AM -0500, Andrew Laski wrote:
> >>On 02/02/2015 05:58 AM, Daniel P. Berrange wrote:
> >>>On Sun, Feb 01, 2015 at 11:20:08AM -0800, Noel Burton-Krahn wrote:
> >>>>Thanks for bringing this up, Daniel.  I don't think it makes sense to have
> >>>>a timeout on live migration, but operators should be able to cancel it,
> >>>>just like any other unbounded long-running process.  For example, there's
> >>>>no timeout on file transfers, but they need an interface report progress
> >>>>and to cancel them.  That would imply an option to cancel evacuation too.
> >>>There has been periodic talk about a generic "tasks API" in Nova for managing
> >>>long running operations and getting information about their progress, but I
> >>>am not sure what the status of that is. It would obviously be applicable to
> >>>migration if that's a route we took.
> >>Currently the status of a tasks API is that it would happen after the API
> >>v2.1 microversions work has created a suitable framework in which to add
> >>tasks to the API.
> >So is all work on tasks blocked by the microversions support ? I would have
> >though that would only block places where we need to modify existing APIs.
> >Are we not able to add APIs for listing / cancelling tasks as new APIs
> >without such a dependency on microversions ?
> 
> Tasks work is certainly not blocked on waiting for microversions. There is a
> large amount of non API facing work that could be done to move forward the
> idea of a task driving state changes within Nova. I would very likely be
> working on that if I wasn't currently spending much of my time on cells v2.

Ok, thanks for the info. So from the POV of migration, I'll focus on the
non-API stuff, and expect the tasks work to provide the API mechanisms

Regards,
Daniel
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