Warm standby vs active-active
A warm standby keeps a small copy in a second region and grows it after a failure. Active-active runs full capacity in both regions all the time. When a region fails for good, the standby takes too long to grow and loses 5.5 percent of orders, and active-active loses under 1 percent.
3 of 3 up · availability 99.9999%
Two rows · 3 of 3 replicas up · load served
Case 1
Orders arrive at 1,200/s. DNS checks each region every 5 s and clients keep an answer for 10 s. At 10:00 one region fails for good. At most 1 percent of orders may fail.
| Measure | Goal | Warm standby | Active-active |
|---|---|---|---|
| Availability | at least 99% | 94.5% Fail | 99.456% Pass |
| p99 latency | under 300 ms | 10.1 s Fail | 180 ms Pass |
| Monthly cost | 56 USD/mo | 62 USD/mo | |
| Error rate | 5.5% | 0.5% |