An online retail platform experiences a complete outage in its primary Google Cloud region (us-east1). The platform architecture uses Cloud SQL for PostgreSQL with a cross-region read replica in us-central1, and a Compute Engine Managed Instance Group (MIG) deployed as a warm standby in us-central1 running at 10% capacity. As the Cloud Architect, you must execute the emergency disaster recovery failover runbook to restore operational production capabilities in us-central1. In what sequence should you execute the failover tasks?
- 1Promote the cross-region Cloud SQL read replica in us-central1 to a standalone primary database instance.
- 2Scale up the warm standby Managed Instance Group (MIG) in us-central1 to 100% production capacity.
- 3Update application configurations with the new primary database endpoint and execute automated health checks.
- 4Update Cloud DNS routing policy records to direct user traffic to the us-central1 load balancer endpoint.
Answer
The correct operational sequence for disaster recovery execution is: 1) Promote the cross-region Cloud SQL read replica in us-central1 to standalone primary, 2) Scale up the warm standby Managed Instance Group in us-central1 to 100% capacity, 3) Update application configurations and execute health checks, 4) Update Cloud DNS routing policies to shift live user traffic to us-central1.
The correct failover sequence ensures data consistency and minimal service disruption: first promote the read replica to enable database write operations, next scale up compute capacity to handle production throughput, then update configuration and verify service health, and finally update DNS records to route end-user traffic to the failover region.
Step-by-Step Solution
Key Concept
Disaster Recovery Failover Execution Sequencing