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Difficulty: MediumResilient Database Configurations and High Availability

A financial technology company is migrating its core transaction ledger application to Amazon Aurora PostgreSQL. The application requires high availability within a single AWS Region, with a Recovery Point Objective (RPO) of zero (no data loss) and a Recovery Time Objective (RTO) of less than 30 seconds. Additionally, the company needs to dynamically scale read operations during peak trading hours. Which database configuration best meets these requirements?

  1. Deploy an Amazon Aurora PostgreSQL DB cluster with a primary writer instance and at least one Aurora Replica in a different Availability Zone, and configure the application to use the cluster endpoint and reader endpoint.Answer
  2. B
    Deploy a single-node Amazon Aurora PostgreSQL DB cluster, and configure an Amazon RDS PostgreSQL Read Replica in a different Availability Zone to serve as the automatic failover target.
  3. C
    Deploy an Amazon Aurora PostgreSQL DB cluster in a Single-AZ configuration, and configure Amazon Route 53 latency routing to automatically redirect write traffic to a read replica during an outage.
  4. D
    Deploy a primary Amazon Aurora PostgreSQL DB instance, configure a standby instance in another Availability Zone, and implement a pilot light replication scheme to sync transaction logs every 10 minutes.

Answer

Deploy an Amazon Aurora PostgreSQL DB cluster with a primary writer instance and at least one Aurora Replica in a different Availability Zone, and configure the application to use the cluster endpoint and reader endpoint.
The correct configuration uses an Amazon Aurora PostgreSQL DB cluster with a primary writer instance and at least one Aurora Replica in a different Availability Zone. Amazon Aurora automatically replicates database storage across three Availability Zones within the region, ensuring an RPO of zero. If the primary instance fails, Aurora automatically fails over to the replica in another Availability Zone in less than 30 seconds (meeting the RTO requirement). The application can write to the cluster endpoint and scale read operations dynamically by using the reader endpoint.

Step-by-Step Solution

1
Evaluate the RPO and RTO requirements to determine the storage and replication design.
Since RPO is zero, synchronous replication at the storage layer is required. Amazon Aurora automatically replicates data across three Availability Zones, ensuring zero data loss.
Asynchronous replication schemes or cross-region setups can introduce replication lag, resulting in an RPO greater than zero.
2
Evaluate the high availability and failover mechanism to meet the RTO requirement.
Deploying an Aurora Replica in a separate Availability Zone enables automatic failover in less than 30 seconds.
Manual intervention, external scripting (e.g., Lambda), or relying on read replicas for standard RDS failover increases failover times and fails the sub-30-second RTO constraint.
3
Address the read scaling requirement.
Direct read queries to the Aurora reader endpoint, which routes traffic across active replicas.
This offloads read traffic from the primary writer instance without impacting write performance.

Key Concept

Amazon Aurora high availability relies on multi-AZ storage replication and Aurora Replicas acting as failover targets with automated failover handling.
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Topics

Resilient Database Configurations and High Availability

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