Google PCA Ensure solution and operations reliability Practice Question
Your organization uses Cloud Spanner for a customer database with a 99.999% availability SLA. You need a Disaster Recovery plan that ensures data consistency with zero RPO in case of a region failure. What should you do?
⚠ Common exam trap
Google Cloud often tests the misconception that read replicas or periodic exports can achieve zero RPO, but only synchronous multi-region replication (as in Spanner's multi-region configurations) guarantees no data loss during a region failure.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a multi-region instance configuration (e.g., nam-eur-asia) for the Spanner instance.
Cloud Spanner multi-region instance configurations (e.g., nam-eur-asia) provide synchronous replication across multiple regions, ensuring strong global consistency and zero RPO. This architecture uses Paxos-based replication to commit writes only after they are durably stored in a majority of regions, so a region failure does not lose any committed data. The 99.999% availability SLA is met by automatic failover within the multi-region setup without manual intervention.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a single-region instance configuration and enable read replicas.
Why it's wrong here
A single-region configuration places all replicas in one region, so a regional failure removes every copy; read replicas only scale reads. Multi-region configuration is what survives region loss, and read replicas suit read-heavy workloads, not disaster recovery.
- ✗
Export the database periodically to Cloud Storage and set up a cross-region load balancer.
Why it's wrong here
Periodic exports are batch snapshots, so any writes after the last export are lost, breaking zero RPO; a load balancer distributes traffic but restores no data. Export suits archival or analytics pipelines, not regional failover for a transactional database.
- ✗
Configure daily backups and store them in Cloud Storage in a different region.
Why it's wrong here
Daily backups capture point-in-time copies, so up to a day of committed transactions is lost on failover, violating zero RPO. Backups are the right mechanism for recovery from logical corruption or accidental deletion, not for continuous regional availability.
- ✓
Use a multi-region instance configuration (e.g., nam-eur-asia) for the Spanner instance.
Why this is correct
A multi-region instance configuration synchronously replicates data across regions using Paxos consensus, so committed writes survive a regional failure with zero data loss. This directly satisfies the stem's zero RPO and consistency requirements, and the 99.999% SLA is only achievable with multi-region configurations, not regional ones.
Go deeper
Related to this question
Learn chapter
Data Migration and Transfer Services
Key term
Disaster recovery
Disaster recovery is a set of policies, procedures, and tools that help an organization restore critical IT systems and data after a disruptive event.
Key term
Multi-region
Multi-region refers to a deployment strategy where IT resources, applications, or data are hosted in multiple geographic locations to improve availability, disaster recovery, and performance.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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