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Difficulty: HardResilient Database Configurations and High Availability

A healthcare provider is deploying a critical patient record application using Amazon RDS for MySQL. The database tier must withstand an Availability Zone (AZ) failure with zero data loss (RPO=0RPO = 0) and support automatic failover in less than 45 seconds45\text{ seconds} (RTO<45 sRTO < 45\text{ s}). The application also requires horizontal scaling of read operations to prevent reporting dashboards from affecting the write performance of the primary database instance. Which database configuration meets these requirements with the least operational complexity?

  1. A
    Deploy an RDS for MySQL DB instance in a single Availability Zone. Create two RDS Read Replicas in different Availability Zones, and configure the application to promote a replica to primary if the primary instance fails.
  2. B
    Deploy an RDS for MySQL Multi-AZ DB instance. Create an RDS Read Replica in a second Availability Zone, and configure an Amazon Route 53 latency routing policy to distribute database connections between the primary instance and the replica.
  3. Deploy an RDS for MySQL Multi-AZ DB cluster. Configure the reporting dashboards to use the reader endpoint of the cluster.Answer
  4. D
    Deploy an RDS for MySQL DB instance in one Region and configure a Warm Standby DB instance in a secondary Region. Use AWS Backup to replicate snapshots hourly, and manually promote the standby instance if a failure occurs.

Answer

Deploy an RDS for MySQL Multi-AZ DB cluster and configure the reporting dashboards to use the reader endpoint of the cluster.
Deploying an RDS for MySQL Multi-AZ DB cluster is correct because it uses synchronous replication across three Availability Zones to ensure zero data loss (RPO=0RPO = 0) and provides automatic failover in under 35 seconds (meeting the RTO<45 sRTO < 45\text{ s} requirement). Additionally, the cluster includes two readable standby instances that can be queried via the reader endpoint to scale reads without the operational complexity of provisioning separate read replicas.

Step-by-Step Solution

1
Analyze the high availability and failover constraints.
The requirements dictate zero data loss (RPO=0RPO = 0) and automatic failover in less than 45 seconds (RTO<45 sRTO < 45\text{ s}), which rules out asynchronous replication methods and standard Multi-AZ DB instances (which take 60–120 seconds).
Identifying the recovery metrics helps narrow the architecture options to synchronous cluster-based deployments.
2
Analyze the read scaling and complexity constraints.
The reporting dashboards require read scaling that does not impact write operations, with the least operational complexity.
This points to a configuration that natively supports readable standby instances without requiring separate read replicas to be provisioned and managed.
3
Select the optimal database deployment option.
An Amazon RDS Multi-AZ DB cluster provides one writer and two readable standby instances across three AZs with synchronous replication, automatic failover under 35 seconds, and a built-in reader endpoint.
This satisfies all RTO, RPO, read scaling, and low operational complexity requirements.

Key Concept

Amazon RDS Multi-AZ DB clusters provide synchronous replication across three Availability Zones with readable standby instances and rapid automatic failover (typically under 35 seconds), satisfying strict RPO, RTO, and read-scaling requirements simultaneously.
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Topics

Resilient Database Configurations and High Availability

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