Explain RTO and RPO, and how they drive disaster recovery design.

Summary

Recovery time objective is how long a service may be down after a disaster; recovery point objective is how much data (measured in time) may be lost. They decide the strategy and its cost: backup and restore (hours, cheapest), pilot light, warm standby, and multi-site active-active (near zero, most expensive).

Longer Answer

RPO drives replication and backup frequency (continuous replication for seconds, nightly backups for a day). RTO drives how much infrastructure is pre-provisioned and automated. Both must be agreed with the business per service, tested in real recovery drills, and include dependencies (a service with a 15-minute RTO that depends on a database with a 4-hour restore really has a 4-hour RTO). Protect backups from the same failure: separate accounts, immutability, and protection against ransomware or accidental deletion.

Key Points

• RTO = downtime allowed; RPO = data loss allowed.
• Strategies from backup/restore to active-active.
• Include dependencies.
• Test restores; isolate backups.