Testing Failover Safely: Game Days, Chaos Experiments and Region Drills

The guide recommends testing failover by progressing from low-risk exercises to full production drills, expanding scope only as confidence grows. It argues that active-active architectures are safest because every region already serves traffic, so a drill simply removes one region from rotation. Control Plane, which publishes the guide, describes how suspending a workload in one location reroutes its global endpoint to the others, making a region drill a reversible configuration change. The testing ladder ranges from monthly tabletop exercises to quarterly full region evacuations, each with guardrails such as limited blast radius and automatic abort conditions tied to SLOs. Key metrics to track include RTO, RPO, latency percentiles, and time to detect and decide.