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Difficulty: MediumResilient Database Configurations and High Availability

A healthcare software provider is deploying a patient management portal on AWS. The relational database backend must remain highly available even if an entire Availability Zone (AZ) suffers an outage. The database configuration must support a Recovery Point Objective (RPO\text{RPO}) of 00 (zero data loss) and a Recovery Time Objective (RTO\text{RTO}) of less than 3535 seconds. Furthermore, the portal experiences frequent read-heavy spikes, requiring the ability to serve read queries directly from standby database nodes within the cluster to optimize performance. Which database architecture should a solutions architect recommend to meet these requirements?

  1. A
    Deploy two independent Single-AZ Amazon RDS DB instances in different Availability Zones, and configure Amazon Route 53 latency routing to distribute traffic between them.
  2. Deploy an Amazon RDS Multi-AZ DB cluster with one primary writer instance and two readable standby instances across three Availability Zones.Answer
  3. C
    Deploy a Single-AZ Amazon RDS DB instance and create two Read Replicas in different Availability Zones, configuring the application to promote a Read Replica to primary during a failure.
  4. D
    Configure a Pilot Light disaster recovery strategy by maintaining a scaled-down Amazon RDS instance in a secondary Availability Zone and restoring data from daily backups during an outage.

Answer

Deploying an Amazon RDS Multi-AZ DB cluster with one primary writer instance and two readable standby instances across three Availability Zones is the correct configuration.
Deploying an Amazon RDS Multi-AZ DB cluster provides synchronous replication across three Availability Zones (ensuring RPO = 0) and automated failover that typically completes in under 35 seconds (meeting the RTO requirement). Crucially, unlike standard Multi-AZ DB instance deployments, the standby instances in a Multi-AZ DB cluster are readable, allowing the application to offload read traffic directly to them.

Step-by-Step Solution

1
Evaluate the Recovery Point Objective (RPO) requirement.
To achieve an RPO of 0 (zero data loss), the database must use synchronous replication across Availability Zones.
Asynchronous replication mechanisms, such as standard RDS Read Replicas, can lead to data loss during failover.
2
Evaluate the Recovery Time Objective (RTO) and read-scaling requirements.
The database must support automatic failover in under 35 seconds and allow read queries to be served from standby nodes.
Standard Multi-AZ DB instance deployments do not support read queries on the standby instance. Multi-AZ DB clusters provide both automatic failover (typically under 35 seconds) and readable standby instances.
3
Select the configuration that satisfies all conditions.
An Amazon RDS Multi-AZ DB cluster meets all RPO, RTO, and read-scaling requirements.
It deploys one writer and two readable standby DB instances across three AZs with synchronous replication and automated failover.

Key Concept

Amazon RDS Multi-AZ DB clusters provide synchronous replication, fast automated failover, and active readable standby instances for scaling read traffic.
Estimated Time:1m 30s
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Topics

Resilient Database Configurations and High Availability

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