Hey guys,

we migrated an OpenStack installation of one of our customers to TripleO RDO when Rocky was released. Back then deployment times were fine, as the whole cluster didn't have that many nodes yet.

In the meantime we upgraded to Ussuri and use 3 controllers and 44 compute nodes by now. Our deployment times exponentially increased with each set of compute nodes we added. With our current setup, a complete deployment run takes about 15 to 16 hours. In our clusters we count the following ressources right now:

VMs: ~ 2100
Networks: ~500
Ports: ~6100
Volumes: ~5700

We implemented ARA for now so we can get exact measures of each ansible-playbook runtime to see what is taking the most time. My question is: How big are your production OpenStack environments and how long does it take you to deploy?

Which methods do you guys use to scale-up compute nodes? (spoiler: --skip-deploy-identifier doesn't seem to work properly)
Is Blacklisting all other Compute nodes the right move? Do you even blacklist the Controllers as well?