Aligning Rto Rpo Architectural Patterns Gcp

What Cloud SQL HA and Regional MIGs Are

Cloud SQL High Availability (HA) mode provides automatic failover and data redundancy by synchronously replicating data between a primary instance and a standby instance located in two different zones within the same region. Combined with a regional Managed Instance Group (MIG) distributed across multiple zones, this pattern provides automated compute and database resilience against zonal failures.

How it meets RTO and RPO Requirements

• RPO Target (Near Zero): Cloud SQL HA uses synchronous block-level disk replication across two zones in a region. Every committed transaction is written to both the primary and standby instances before acknowledgement, resulting in an RPO that is effectively zero in the event of a zone outage.
• RTO Target (< 5 minutes): When a zonal outage or primary instance failure occurs, Cloud SQL detects the issue via internal health checks and automatically switches traffic to the standby instance in the healthy zone. This failover process typically completes in under 2–3 minutes without changing database endpoints or IP configurations. Simultaneously, the regional MIG maintains compute availability in surviving zones.

Key advantages and capabilities

• Zero manual intervention: Automatic failover for both compute and database layers.
• Preserved endpoints: Cloud SQL maintains the same IP address across failover, eliminating application-tier configuration changes.
• Synchronous disk durability: Writes are mirrored to the standby zone immediately.
• Regional traffic distribution: The regional MIG automatically balances application compute capacity across multiple zones.

Why this is optimal

This pattern directly aligns with an RPO of near zero and an RTO under 5 minutes without requiring custom orchestrators, manual promotion scripts, or complex multi-region coordination.