I’m in the process of setting up a CockroachDB cluster and could use some guidance. I have 2 physical servers and plan to deploy a total of 5 VMs: 3 on one host and 2 on the other. This setup is intended to support 20,000 users.

Here are a few questions I’m hoping the community can help with:

PgBouncer Placement:
I’m debating where to place PgBouncer in this architecture. Should it be deployed on top of HAProxy, or would it be more effective on top of each CockroachDB instance? I’d love to hear your thoughts on the best practice for connection pooling in this scenario.

vCPU Recommendations:
Given the need to accommodate 20,000 users, how many vCPUs should I allocate for the entire cluster? I’m looking for advice on the optimal number of vCPUs to ensure efficient performance without over-provisioning.