[openstack-dev] [Nova] Ceilometer vs. Nova internal metrics collector for scheduling (was: New DB column or new DB table?)

Andrew Laski andrew.laski at rackspace.com
Fri Jul 19 12:37:46 UTC 2013

On 07/19/13 at 07:04am, Sean Dague wrote:
>On 07/19/2013 06:18 AM, Day, Phil wrote:
>>Ceilometer is a great project for taking metrics available in Nova and other systems and making them available for use by Operations, Billing, Monitoring, etc - and clearly we should try and avoid having multiple collectors of the same data.
>>But making the Nova scheduler dependent on Ceilometer seems to be the wrong way round to me - scheduling is such a fundamental operation that I want Nova to be self sufficient in this regard.   In particular I don't want the availability of my core compute platform to be constrained by the availability of my (still evolving) monitoring system.
>>If Ceilometer can be fed from the data used by the Nova scheduler then that's a good plus - but not the other way round.
>I assume it would gracefully degrade to the existing static 
>allocators if something went wrong. If not, well that would be very 
>Ceilometer is an integrated project in Havana. Utilization based 
>scheduling would be a new feature. I'm not sure why we think that 
>duplicating the metrics collectors in new code would be less buggy 
>than working with Ceilometer. Nova depends on external projects all 
>the time.

I tend to agree here.  It's worth at least doing the due diligence to 
see if this is something that could fit into Ceilometer.  Or maybe 
there's code that can be pulled out of Ceilometer and put into oslo to 
hanlde this.  It doesn't make sense to duplicate effort if we can take 
advantage of already implemented code.

>If we have a concern about robustness here, we should be working as 
>an overall project to address that.
>	-Sean
>Sean Dague
>OpenStack-dev mailing list
>OpenStack-dev at lists.openstack.org

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