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

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)