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Zorluk: OrtaDisaster Recovery and Business Continuity Execution

A healthcare enterprise runs its electronic health record (EHR) analytics system on Google Cloud. The primary deployment operates in region `us-central1` using Cloud SQL for PostgreSQL and Compute Engine Managed Instance Groups (MIGs). To meet disaster recovery (DR) objectives of Recovery Time Objective (RTO) under 15 minutes and Recovery Point Objective (RPO) under 1 minute while minimizing baseline idle infrastructure costs, you implement a warm standby pattern in region `us-east4`. You configure a cross-region read replica for Cloud SQL and maintain a minimal scaled-down MIG in `us-east4`. During a simulated regional failover drill in `us-east4`, the Cloud SQL read replica is successfully promoted to primary, but scaling out the DR MIG to handle production traffic fails immediately with instance provisioning errors. What is the most likely root cause of this failure during DR execution?

  1. The organization did not proactively request and verify sufficient regional Compute Engine CPU and instance quotas in us-east4 prior to executing the failover.Cevap
  2. B
    The architecture failed to replace Cloud SQL with Cloud Spanner, which is required to achieve cross-region replication with an RPO under 1 minute.
  3. C
    The replication traffic exceeded HA VPN tunnel throughput caps between GCP regions, blocking MIG compute instance startup.
  4. D
    The DR MIG instances could not communicate with the database because VPC Network Peering between primary and DR VPCs does not support transitive routing.

Cevap

The organization did not proactively request and verify sufficient regional Compute Engine CPU and instance quotas in us-east4 prior to executing the failover.
When executing a regional failover using a pilot light or warm standby pattern, scaling up Compute Engine Managed Instance Groups in the recovery region requires available resource quotas (such as regional CPU limits and IP allocations). Because GCP quotas are managed per region, failing to request and verify quota increases in the secondary region in advance causes immediate instance provisioning failures when scaling out during a DR event.

Adım Adım Çözüm

1
Analyze the disaster recovery strategy and architecture components
Warm standby strategy using Cloud SQL cross-region read replica and a scaled-down MIG in the secondary region (us-east4).
Understanding the baseline state helps identify which component failed during scale-out.
2
Evaluate the symptom observed during DR execution
Database promotion succeeded, but MIG auto-scaling/scale-out failed immediately with instance provisioning errors.
The failure occurred specifically when attempting to rapidly allocate compute capacity in the secondary region.
3
Identify GCP platform constraints in secondary regions
GCP quotas (e.g., N2 CPUs, In-Use IP addresses) are regional. A secondary region with low default quotas will reject rapid scale-out requests.
Ensuring capacity availability requires proactively requesting quota increases in secondary DR regions well before an actual failover event.

Anahtar Kavram

Disaster Recovery Execution and Regional Resource Quota Planning
Tahmini Süre:1m 30s
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Konular

Disaster Recovery and Business Continuity Execution

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