QuestionQ265

Designing and planning a cloud solution architecture

A large healthcare provider’s main electronic health record (EHR) application runs on Compute Engine instances and uses a Cloud SQL for PostgreSQL database, all in the us-west1 region.

A new regulatory mandate requires implementation and documentation of a business continuity plan (BCP). The plan must ensure that the EHR application can be completely recovered and operating in another geographical region, with a recovery time objective (RTO) of two hours and a recovery point objective (RPO) of 15 minutes.

You need to design a disaster recovery strategy that fulfills these strict BCP requirements. What should you do?

  • A Deploy active managed instance groups (MIGs) in both us-west1 and us-east1, fronted by a global external HTTP(S) Load Balancer. For the database, use a cross-region read replica in us-east1, and rely on load balancer health checks to automatically fail over all traffic during an outage.
  • B Use Terraform to define the application’s compute infrastructure. During a disaster, configure the Cloud SQL database in us-west1 to use a cross-region read replica in us-east1, build the environment in us-east1, and promote the replica.
  • C Take daily snapshots of the Compute Engine disks and Cloud SQL database. Copy these snapshots to a Cloud Storage bucket in us-east1. During a disaster, manually restore the virtual machines (VMs) and database from the latest snapshots
  • D Deploy a regional MIG in us-west1 for high availability, and rely on the Google Cloud SLA to ensure the region remains online.
Explanation

A pre-established cross-region Cloud SQL read replica provides continuously replicated data in the secondary region and can be promoted to a writable primary during a regional outage. Defining the Compute Engine application infrastructure with Terraform enables the secondary environment to be recreated consistently within the two-hour recovery window. The replica’s replication lag must be monitored and kept within 15 minutes to meet the RPO. Google Cloud documents cross-region replicas and promotion as the Cloud SQL regional-disaster-recovery mechanism; backup/restore takes longer, and replica promotion is required before the secondary database can accept writes.

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