A healthcare SaaS provider hosts a critical patient portal on AWS. The application tier ru… — AWS Certified Solutions Architect - Associate

A healthcare SaaS provider hosts a critical patient portal on AWS. The application tier runs on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB) in the primary Region (us-east-1). The database tier runs on an Amazon Aurora PostgreSQL DB cluster. The provider wants to implement a cross-region disaster recovery (DR) strategy in a secondary Region (us-west-2). The business SLA mandates a Recovery Time Objective (RTO) of $15\text{ minutes}$ and a Recovery Point Objective (RPO) of $1\text{ minute}$ . The solution must minimize infrastructure costs during normal operations in the primary Region.

Which combination of actions will meet these requirements at the lowest cost? (Select TWO.)

Configure Amazon Aurora Global Database with a secondary DB cluster in the secondary Region, and configure the secondary DB cluster with zero DB instances under normal operating conditions.Answer
Pre-deploy the Application Load Balancer and the Auto Scaling group in the secondary Region with both the desired and minimum capacity set to $0$ , and use a failover script to scale up the instances during a disaster recovery event.Answer
C
Deploy an Amazon RDS PostgreSQL Read Replica in the secondary Region, and configure Amazon Route 53 latency routing to automatically promote the replica to primary if the primary database becomes unresponsive.
D
Schedule hourly exports of the DB cluster snapshots to Amazon S3, replicate the snapshots to the secondary Region using S3 Cross-Region Replication (CRR) with the S3 Glacier Flexible Retrieval storage class, and restore the DB cluster from the backup during failover.
E
Deploy a Warm Standby compute environment in the secondary Region by running EC2 instances at $50\%$ capacity on smaller instance types, and configure Route 53 failover routing to dynamically scale up the instance sizes during failover.

Answer

Configure Amazon Aurora Global Database with a secondary DB cluster containing zero DB instances, and pre-deploy the Application Load Balancer and Auto Scaling group with the capacity set to zero, scaling up the instances and databases via automation during failover.

To satisfy a Recovery Point Objective (RPO) of

1\text{ minute}

and a Recovery Time Objective (RTO) of

15\text{ minutes}

at the lowest cost, a Pilot Light DR pattern is ideal. By leveraging Amazon Aurora Global Database, storage replication is continuous and automatic with sub-second latency, satisfying the

1\text{-minute}

RPO. Keeping the secondary database cluster headless (zero DB instances) under normal conditions ensures zero database compute costs. Pre-deploying the Application Load Balancer and configuring the Auto Scaling group with a desired capacity of

0

ensures zero compute costs for the application tier during normal operations. During a disaster, automated scripts can spin up DB instances in the secondary Region, promote the secondary Aurora cluster, and scale up the Auto Scaling group to launch EC2 instances, recovering the application well within the

15\text{-minute}

RTO.

Step-by-Step Solution

Analyze the database replication and RPO requirement.

To meet the

1\text{-minute}

RPO, continuous physical or logical replication is required. Amazon Aurora Global Database replicates storage updates across Regions with latency of less than

1\text{ second}

, meeting the RPO.

Traditional backup methods like hourly snapshots or S3 backups cannot guarantee a

1\text{-minute}

RPO.

Analyze the database compute and cost requirement.

Configure a secondary DB cluster in the Global Database with zero running DB instances (headless cluster) to eliminate running compute costs during normal operations.

During failover, adding a new DB instance to the secondary cluster and promoting it takes only a few minutes, which is well within the

15\text{-minute}

RTO.

Analyze the application tier compute and cost requirement.

Deploy the Application Load Balancer and Auto Scaling group in the secondary Region with desired capacity set to

0

This Pilot Light strategy incurs zero EC2 running costs under normal conditions. During failover, the Auto Scaling group capacity can be scaled up to launch EC2 instances and receive traffic within the

15\text{-minute}

window.

Key Concept

Disaster recovery (DR) architectures on AWS utilize different patterns (such as Pilot Light and Warm Standby) to balance cost, Recovery Time Objective (RTO), and Recovery Point Objective (RPO). A Pilot Light architecture keeps database replication active (often headless or minimal) and compute resources scaled down to zero, provisioning them dynamically via automated scripts during failover to meet RTOs in the range of tens of minutes while minimizing baseline run costs.

Estimated Time:2m 30s

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