Work out disaster recovery cost instantly with clear inputs, formula shown and shareable results.
The four standard DR strategies form a cost-versus-recovery-time ladder: backup and restore costs a few percent of production and recovers in hours; pilot light keeps core services running at around 15 percent; warm standby runs a scaled-down full copy at roughly half; active-active doubles cost and recovers instantly. Replication transfer is a separate line in all but the cheapest.
DR cost by strategy
DR compute = primary cost x strategy factor (0.05 backup, 0.15 pilot light, 0.5 warm, 1.0 active-active); plus replication transfer
Work backwards from the business RTO and RPO. Paying for active-active when the business tolerates four hours of downtime is waste; using backup and restore when it tolerates fifteen minutes is negligence.
Because it creates false confidence. A DR plan that has never been exercised typically fails on dependencies nobody documented, and the failure is discovered during the incident.