A production database has an RTO of 4 hours and an RPO of 1 hour. Which disaster recovery strategy is the most cost-effective while meeting both objectives?
Show answer and explanation
Answer: C
A pilot light keeps only the minimum running in the recovery Region — typically continuous data-layer replication — so the one-hour RPO is met by replication, not by snapshot timing. Because the core infrastructure is pre-built, the failover just starts and scales the application tier, which comfortably fits a four-hour RTO, while the standing idle footprint is small and cheap.
Warm standby also meets both numbers but keeps a scaled-down full application running continuously, so it costs more; daily snapshots would lose up to a day of data against the one-hour RPO.
Why the other options are wrong
- A. Active/active runs complete production capacity in two Regions continuously, which is the most expensive DR strategy and far exceeds what a 4-hour/1-hour objective requires.
- B. Warm standby satisfies both targets but keeps a permanently running scaled-down copy of the whole workload, so its ongoing cost is higher than a pilot light even though it is not the priciest option.
- D. Restore from daily snapshots loses as much as a day of data when failure lands just before the next snapshot, badly violating the one-hour RPO however cheap it is.