Question

Difficulty: MediumResilient Database Configurations and High Availability

A retail company runs a production transaction-processing application on an Amazon RDS for MySQL DB instance. The database must be highly resilient to Availability Zone outages with a Recovery Time Objective (RTO) of less than 120 seconds. Additionally, the application requires read scaling to handle heavy reporting queries during business hours without impacting write operations on the primary database instance.

Which two database configurations should the solutions architect choose to meet these requirements? (Select TWO.)

  1. Deploy the Amazon RDS DB instance in a Multi-AZ deployment.Answer
  2. Create Amazon RDS Read Replicas and direct read traffic to the read replica endpoints.Answer
  3. C
    Deploy the Amazon RDS DB instance in a Multi-AZ deployment and configure the application to route read queries to the standby database instance.
  4. D
    Deploy a single-AZ DB instance and configure the application to automatically promote a Read Replica to primary during a primary database outage.
  5. E
    Deploy the database in a single-AZ configuration and set up an Amazon Route 53 latency routing policy with health checks to automatically fail over database write traffic to a Read Replica.

Answer

Deploy the database in a Multi-AZ configuration to achieve high availability and low RTO, and create RDS Read Replicas to scale read performance.
To meet the requirements, the database must support automatic failover for high availability and read scaling. A Multi-AZ deployment creates a primary DB instance and a synchronous standby replica in a different Availability Zone. If the primary instance fails, RDS automatically performs a failover to the standby, achieving a low RTO. To scale read queries without affecting the primary write performance, creating RDS Read Replicas and directing reporting traffic to the read replica endpoints is the correct approach.

Step-by-Step Solution

1
Identify high availability and RTO requirements.
Determine that a Multi-AZ deployment is required to provide synchronous replication and automatic failover in under 120 seconds.
A single-AZ DB instance with read replicas does not support automatic, low-RTO failover.
2
Identify read scaling requirements.
Determine that RDS Read Replicas are needed to handle reporting queries and offload read traffic from the primary database.
The standby DB instance in a Multi-AZ DB instance configuration is passive and cannot serve read traffic.
3
Select the correct combination of configurations.
Combine a Multi-AZ deployment for failover/HA with one or more Read Replicas for read scaling.
This satisfies both the HA/failover RTO requirements and the read scalability constraints.

Key Concept

Distinguishing between RDS Multi-AZ deployments for high availability/failover and RDS Read Replicas for scaling read operations.
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