Compare backup-and-restore, pilot light, warm standby, and multi-site DR strategies.
AWS · Advanced level
Answer
Backup-and-restore is cheapest and slowest; pilot light keeps core pieces ready; warm standby runs a scaled-down environment; multi-site runs active environments. The right choice depends on business RTO/RPO and cost tolerance.
Technical explanation
The four DR strategies are a cost-versus-readiness spectrum; choose based on business impact.
Availability design should start from business impact, RTO/RPO, dependency mapping, and failure-mode testing, not only from deploying resources in multiple AZs.
Stateless compute, resilient data stores, health checks, rollback, backups, and game days are all required to prove resilience.
Lower recovery targets require higher cost, more automation, replicated data, pre-provisioned capacity, and regularly tested runbooks.
Hands-on example
1. Draw the workload dependency map, then define target RTO/RPO with the business owner.
2. Implement multi-AZ or multi-Region components required by those targets, including data replication and automated provisioning.
3. Run a game day: instance failure, AZ impairment, database failover, restore test, or regional failover depending on scope.
4. Measure actual recovery time/data loss and update the architecture or runbook if targets are missed.
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