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On 4/3/2017 5:30 PM, Matt Riedemann wrote:
> On 4/3/2017 2:21 PM, Mathieu Gagné wrote:
>>
>> I would like to share our private implementation (based on Mitaka):
>> https://gist.github.com/mgagne/9402089c11f8c80f6d6cd49f3db76512
>>
>> The implementation makes it so Cinder leverages the existing Nova
>> external-events endpoint to trigger the BDM update and iSCSI rescan on
>> the host.
>
> I like this a lot better than adding a new REST API to Nova to handle
> orchestrating this from the start.
>
>>
>> As always, the guest needs to update the partition table/filesystem if
>> it wants to benefit from the new free space.
>>
>> Let me know if this is an implementation you want me to contribute
>> upstream.
>>
>
> I didn't read the patch in detail, but if you're interested in
> contributing this upstream we could use a simple spec to start the
> process. Note that nova spec freeze for Pike is April 13.
>

One thing we'd have to consider with this is if nova is new enough to 
handle the external event. I think we'd bump the microversion in the 
compute API and then on the cinder side, it asks the compute API for 
available versions and if the version available is new enough to handle 
the event, then you move forward, else you fail on the cinder API side 
since you know nova can't handle the external event.

-- 

Thanks,

Matt