[kmontrose]

David means a single primary, there's a read-only replica for in DC failover and a read-only replica in our other DC for "New York is getting hit by another hurricane"-failover.

A few services hit the read replicas instead of the primary (our API, for example, moves what it can when it can), but the code for stackoverflow.com is almost entirely querying a single (quite beefy) box.

We can and do sometimes run without either replica in the AG, though we prefer not to except for scheduled maintenance.