[Openstack-operators] Ephemeral instances in RBD issue

David Moreau Simard dmsimard at iweb.com
Wed Oct 29 19:41:05 UTC 2014

Good to know..

I'm aware of the Havana and Icehouse branches but are these fixes upstream in Juno ?

David Moreau Simard

> On Oct 29, 2014, at 3:34 PM, Abel Lopez <alopgeek at gmail.com> wrote:
> So, I figured out why this was happening.
> The gist of it is, the direct_snapshot doesn't start the domain back up. I contacted inktank and they're adding what I found to their fork.
> The long story:
> in nova/virt/libvirt/driver.py, the snapshot method does everything. the code doesn't support live snapshot for lvm or rbd, so we have to do a cold snapshot.
> We go into 'managedSave' ( the instance is suspended to quiesce I/O), the snapshot is taken, then much later, we start a new domain based on the save.
> The last commit to jdurin's fork splits snapshot right after the 'try direct snapshot' and adds a 'generic_snapshot' method. The code for starting up the domain again is in 'generic_snapshot' which only gets called if the exception "ImageUnacceptable" gets raised.
> as a quick hack, I just copied the 'new_dom' lines into 'snapshot' method and HUZZAH, it works as expected.
> Hopefully we'll see a new commit to jdurgin's fork for icehouse and havana soon.
> On Oct 26, 2014, at 6:08 AM, Simon Leinen <simon.leinen at switch.ch> wrote:
>> Abel Lopez writes:
>>> I saw this last commit to jdurgin's nova fork which solves the issue (
>>> https://github.com/jdurgin/nova/commit/ea4b5369e4bec4dd7a0ce9f68769600329cda6c6
>>> )
>>> now a snapshot happens in seconds. 
>>> The problem that we've introduced however, is that about 15-20m after
>>> we do a snapshot, the VM is powered off.
>>> Every time.
>> Ouch! Have you checked the logs (nova-compute and maybe libvirtd's)?
>>> I can start the instance back up with `nova start`, but I am leery of
>>> pushing this out to prod and having to tell users to expect a shutdown
>>> after a snapshot.
>> Understood.
>>> Anyone else using this in Havana?
>> Not me, but I'm sympathetic with your worries, and want this resolved as
>> well.  We're using Icehouse with RBD, currently without the "ephemeral"
>> patches, but we would really like to (re-) activate that part of the
>> integration soon.
>> It's maybe worth asking on #ceph or posting to one of the CEPH mailing
>> lists, too.
>> Good luck,
>> -- 
>> Simon.
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