Ack, your insight is very interesting.

Back at Citus/Microsoft, we typically saw around a 30% performance drop with synchronous replication on EBS-backed Postgres. I’d expect something in that ballpark for RDS and Crunchy as well. For NVMe-backed Postgres, we haven’t yet measured the impact of quorum-based replication, and it’s certainly possible the overhead ends up being higher than 30%.

That said, the single-node margins are already quite substantial, over 2× in all cases and up to 5× versus RDS in our benchmarks. Even with a meaningful HA penalty, NVMe-backed setups could still remain very compelling from a performance perspective. We’ve just started running HA benchmarks, so stay tuned.

Side note local NVMe backed Postgres is for perf is not new - many enterprise companies like Datadog and Instacart run their performance critical services on them, though self-managed.

In regard to RTO for single-node setups, it wouldn’t be great (at least minutes) in most systems, since recovery still needs to happen from backups.

Overall, very useful feedback. Thanks again for chiming in!