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Difficulty: MediumResilient Database Configurations and High Availability

A logistics company is migrating its core order processing system to Amazon RDS. The database must be highly available across multiple Availability Zones with a Recovery Time Objective (RTO) of less than 2 minutes and a Recovery Point Objective (RPO) of 0 (no data loss). Additionally, the solutions architect must scale read performance horizontally to handle reporting queries without impacting write latency on the primary database instance.

Which combination of database configuration and application routing strategies will meet these requirements? (Select TWO.)

  1. A
    Deploy the database as a standard Amazon RDS Multi-AZ DB instance deployment and route read queries to the standby instance.
  2. Deploy the database as an Amazon RDS Multi-AZ DB cluster with one writer and two readable standby DB instances.Answer
  3. C
    Deploy a single-AZ Amazon RDS DB instance and configure a cross-AZ Read Replica, using Amazon Route 53 to automatically promote the replica during an outage.
  4. Configure the application to route write queries to the cluster endpoint and read queries to the reader endpoint of the DB cluster.Answer
  5. E
    Use Amazon Route 53 latency-based routing to distribute database write traffic between the primary database instance and the read replica.

Answer

Deploy the database as an Amazon RDS Multi-AZ DB cluster with one writer and two readable standby DB instances, and configure the application to route write queries to the cluster endpoint and read queries to the reader endpoint of the DB cluster.
Deploying an Amazon RDS Multi-AZ DB cluster provides a primary writer instance and two readable standby instances across three Availability Zones, ensuring automatic failover under 2 minutes and zero data loss (RPO of 0) via semi-synchronous replication. The application can scale reads horizontally by routing queries to the reader endpoint, which load-balances the traffic among the standby instances, while routing writes to the cluster endpoint.

Step-by-Step Solution

1
Identify the high availability and zero data loss (RPO = 0) requirements during an Availability Zone outage.
Determine that standard single-instance or asynchronous replica configurations are insufficient, and a synchronous or semi-synchronous replication method (such as RDS Multi-AZ or Aurora) is required.
Multi-AZ deployments provide automatic failover and ensure data is replicated to another AZ before writes are committed, satisfying the RPO of 0 and RTO under 2 minutes.
2
Evaluate how to support horizontal read scaling alongside high availability in RDS.
Identify that a standard Multi-AZ DB instance has a passive standby that cannot be read from, whereas an RDS Multi-AZ DB cluster provides two readable standby instances.
Choosing the Multi-AZ DB cluster deployment enables both high availability and horizontal read scaling off the standby instances.
3
Determine the proper application routing mechanism to separate reads and writes in the cluster.
Route write operations to the cluster endpoint (pointing to the primary writer) and read operations to the reader endpoint (which load-balances reads to the standby instances).
This separation allows the application to scale reads horizontally without overloading the primary writer database instance.

Key Concept

Amazon RDS Multi-AZ DB cluster configurations for high availability and horizontal read scaling.
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Topics

Resilient Database Configurations and High Availability

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