[openstack-dev] [nova] bug 1334398 and libvirt live snapshot support

Matt Riedemann mriedem at linux.vnet.ibm.com
Fri Dec 5 20:12:44 UTC 2014

On 12/5/2014 1:32 PM, Sean Dague wrote:
> On 12/05/2014 01:50 PM, Matt Riedemann wrote:
>> In Juno we effectively disabled live snapshots with libvirt due to bug
>> 1334398 [1] failing the gate about 25% of the time.
>> I was going through the Juno release notes today and saw this as a known
>> issue, which reminded me of it and was wondering if there is anything
>> being done about it?
>> As I recall, it *works* but it wasn't working under the stress our
>> check/gate system puts on that code path.
>> One thing I'm thinking is, couldn't we make this an experimental config
>> option and by default it's disabled but we could run it in the
>> experimental queue, or people could use it without having to patch the
>> code to remove the artificial minimum version constraint put in the code.
>> Something like:
>> if CONF.libvirt.live_snapshot_supported:
>>     # do your thing
>> [1] https://bugs.launchpad.net/nova/+bug/1334398
> So, it works. If you aren't booting / shutting down guests at exactly
> the same time as snapshotting. I believe cburgess said in IRC yesterday
> he was going to take another look at it next week.
> I'm happy to put this into dansmith's pattented [workarounds] config
> group (coming soon to fix the qemu-convert bug). But I don't think this
> should be a normal libvirt option.
> 	-Sean

Yeah the [workarounds] group is what got me thinking about it too as a 
config option, otherwise I think the idea of an [experimental] config 
group has come up before as a place to put 'not tested, here be dragons' 
type stuff.



Matt Riedemann

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