[ops][largescale-sig] How many compute nodes in a single cluster ?

Arnaud Morin arnaud.morin at gmail.com
Tue Feb 2 17:37:13 UTC 2021

Hey all,

I will start the answers :)

At OVH, our hard limit is around 1500 hypervisors on a region.
It also depends a lot on number of instances (and neutron ports).
The effects if we try to go above this number:
- load on control plane (db/rabbit) is increasing a lot
- "burst" load is hard to manage (e.g. restart of all neutron agent or
  nova computes is putting a high pressure on control plane)
- and of course, failure domain is bigger

Note that we dont use cells.
We are deploying multiple regions, but this is painful to manage /
understand for our clients.
We are looking for a solution to unify the regions, but we did not find
anything which could fit our needs for now.


Arnaud Morin

On 28.01.21 - 14:24, Thierry Carrez wrote:
> Hi everyone,
> As part of the Large Scale SIG[1] activities, I'd like to quickly poll our
> community on the following question:
> How many compute nodes do you feel comfortable fitting in a single-cluster
> deployment of OpenStack, before you need to scale it out to multiple
> regions/cells/.. ?
> Obviously this depends on a lot of deployment-dependent factors (type of
> activity, choice of networking...) so don't overthink it: a rough number is
> fine :)
> [1] https://wiki.openstack.org/wiki/Large_Scale_SIG
> Thanks in advance,
> -- 
> Thierry Carrez (ttx)

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