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Difficulty: HardDeveloping Procedures for Business Continuity and Disaster Recovery Validation

A financial analytics enterprise hosts a critical transaction processing workload on Google Cloud across a primary region (us-central1) and a disaster recovery target region (us-east4). The application uses Compute Engine Managed Instance Groups (MIGs) and Cloud SQL, with a business mandate requiring a Recovery Time Objective (RTO) of 45 minutes and a Recovery Point Objective (RPO) of 15 minutes. During an unannounced DR validation drill, the automated failover process failed: scaling up the secondary MIG in us-east4 was rejected due to hitting default regional CPU quota limits, and application traffic was diverted to us-east4 before database replica promotion completed, causing widespread write transaction errors. Which disaster recovery validation procedure should you establish to prevent these failures in future drills?

  1. Automate pre-drill validation tasks to audit and reserve regional resource quotas in us-east4, and enforce step-by-step dependency gating that verifies database replica promotion and health checks before updating DNS and load balancer traffic routing.Answer
  2. B
    Configure the automated DR script to request dynamic regional CPU quota increases at the moment failover starts, and immediately update global DNS records to begin traffic migration to achieve the minimum RTO.
  3. C
    Re-architect the secondary DR environment into a cold-standby strategy that restores Cloud SQL instances from daily Cloud Storage export snapshots upon failover initiation to circumvent regional quota constraints.
  4. D
    Migrate the primary Cloud SQL database to a single-region Cloud Spanner instance to eliminate database replica promotion delays during DR validation without modifying regional compute quota management procedures.

Answer

Automate pre-drill validation tasks to audit and reserve regional resource quotas in us-east4, and enforce step-by-step dependency gating that verifies database replica promotion and health checks before updating DNS and load balancer traffic routing.
The optimal DR validation procedure combines proactive quota verification in the secondary region with orchestrated failover sequencing. Pre-verifying quota limits ensures that Compute Engine MIGs can scale to meet workload demands without unexpected capacity rejections. Sequential dependency gating guarantees that data tiers are fully promoted to primary read/write status and pass health checks before traffic ingress points (DNS and load balancers) are updated, preventing write errors during switchover.

Step-by-Step Solution

1
Analyze the DR drill failure causes
Identified two failure points: regional CPU quota exhaustion in us-east4 and premature traffic routing before database promotion completed.
DR procedures must address capacity readiness and execution order.
2
Evaluate capacity validation procedures
Proactive quota checks and capacity reservations in target regions ensure compute scaling will not be rejected during a drill or real emergency.
Quota approval involves manual/automated evaluation delays and cannot be relied on during runtime failover.
3
Establish orchestration and dependency validation steps
Enforce strict sequential ordering: promote database replica -> confirm database health -> switch network routing.
Routing live application traffic before database promotion leads to broken writes and transaction loss.

Key Concept

Developing Procedures for Business Continuity and Disaster Recovery Validation
Estimated Time:2m 0s
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Developing Procedures for Business Continuity and Disaster Recovery Validation