[Openstack-operators] Ephemeral instances in RBD issue

Abel Lopez alopgeek at gmail.com
Wed Oct 29 19:44:16 UTC 2014

From what I've seen, yes, full support for RBD ephemeral instances is in Juno.
Just haven't played with it in my lab yet.

On Oct 29, 2014, at 12:41 PM, David Moreau Simard <dmsimard at iweb.com> wrote:

> 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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