There are two types of failover in RDS: - Single instance, if the instance dies they start a new one and mount the same storage. This can take some time, in ge

There are two types of failover in RDS: - Single instance, if the instance dies they start a new one and mount the same storage. This can take some time, in general under 5min but I have seen it take 45min, especially for the large instance types. - Multi A-Z, they run a hot standby with replicated and physically separated storage. Failover takes about a minute. The replication happens at storage level, every write has to be acknowledged by both availability zones. I'm not sure if Postgres is always running or if it gets started when failing over. I guess you could replicate this using drbd.