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Difficulty: MediumDisaster Recovery and Business Continuity Execution

A financial media company operates a real-time news analytics system hosted in Google Cloud's us-central1 region. The platform processes high-throughput data streams using Compute Engine Managed Instance Groups (MIGs) and stores user subscription profiles in Cloud SQL for PostgreSQL. The company requires a disaster recovery (DR) strategy for an unrecoverable outage in us-central1. The business mandates a Recovery Point Objective (RPO) of near zero (< 1 minute) and a Recovery Time Objective (RTO) under 15 minutes. To minimize idle infrastructure costs, compute resources in the secondary region (us-east4) should only be scaled up during an actual failover execution. Which disaster recovery execution strategy satisfies these requirements?

  1. Deploy a Pilot Light strategy: maintain cross-region read replicas for Cloud SQL in us-east4, and keep a minimal scaled-down MIG in us-east4; during failover, promote the Cloud SQL replica to primary and autoscaling expands the MIG.Answer
  2. B
    Deploy a Cold Standby strategy: schedule hourly Cloud SQL export dumps to a Multi-Regional Cloud Storage bucket and recreate the Compute Engine MIG and database from backups in us-east4 after an outage occurs.
  3. C
    Migrate the subscription database from Cloud SQL to Cloud Spanner across a single-region regional configuration and configure Compute Engine MIGs across two zones in us-central1.
  4. D
    Deploy a Warm Standby strategy: establish VPC Network Peering between us-central1 and us-east4, and rely on peered transitivity so secondary instances read directly from the primary us-central1 database during regional isolate tests.

Answer

Deploying a Pilot Light DR pattern with cross-region Cloud SQL read replicas and a minimal scaled-down Compute Engine MIG in the secondary region meets the near-zero RPO and 15-minute RTO requirements while optimizing cost.
The correct strategy combines continuous cross-region database replication (Cloud SQL read replica in us-east4) with a minimal compute footprint (scaled-down MIG). When a failure occurs in the primary region, promoting the database replica and scaling out the MIG fulfills the near-zero RPO and sub-15 minute RTO requirements without paying for full idle compute capacity.

Step-by-Step Solution

1
Evaluate RPO requirements against data replication patterns.
Near-zero RPO (< 1 min) requires continuous data replication. Cloud SQL cross-region read replicas provide continuous asynchronous replication to us-east4.
Backup-and-restore or periodic export dump strategies introduce data loss equal to the backup interval.
2
Evaluate RTO and cost requirements against compute failure strategy.
Keeping a minimal MIG footprint in us-east4 (Pilot Light) ensures rapid capacity expansion within minutes while keeping idle compute cost low.
Provisioning full duplicate infrastructure (Hot Standby) would incur unnecessary idle compute cost, while spinning up from scratch (Cold Standby) risks missing the 15-minute RTO.

Key Concept

Disaster Recovery Patterns (Pilot Light vs Warm/Cold Standby) and RPO/RTO Alignment in GCP
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Topics

Disaster Recovery and Business Continuity Execution

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