Learn the best solution to ensure high availability and minimal downtime for a business-critical web application running on Amazon EC2 instances with an Aurora PostgreSQL database.
Table of Contents
Question
A company is running a business-critical web application on Amazon EC2 instances behind an Application Load Balancer. The EC2 instances are in an Auto Scaling group. The application uses an Amazon Aurora PostgreSQL database that is deployed in a single Availability Zone. The company wants the application to be highly available with minimum downtime and minimum loss of data.
Which solution will meet these requirements with the LEAST operational effort?
A. Place the EC2 instances in different AWS Regions. Use Amazon Route 53 health checks to redirect traffic. Use Aurora PostgreSQL Cross-Region Replication.
B. Configure the Auto Scaling group to use multiple Availability Zones. Configure the database as Multi-AZ. Configure an Amazon RDS Proxy instance for the database.
C. Configure the Auto Scaling group to use one Availability Zone. Generate hourly snapshots of the database. Recover the database from the snapshots in the event of a failure.
D. Configure the Auto Scaling group to use multiple AWS Regions. Write the data from the application to Amazon S3. Use S3 Event Notifications to launch an AWS Lambda function to write the data to the database.
Answer
B. Configure the Auto Scaling group to use multiple Availability Zones. Configure the database as Multi-AZ. Configure an Amazon RDS Proxy instance for the database.
Explanation
The correct answer is B. Configure the Auto Scaling group to use multiple Availability Zones. Configure the database as Multi-AZ. Configure an Amazon RDS Proxy instance for the database.
- Placing EC2 instances in multiple Availability Zones within an Auto Scaling group ensures high availability of the application tier. If one AZ experiences issues, the application remains accessible from other AZs.
- Configuring the Aurora PostgreSQL database as Multi-AZ enables automatic failover to a standby instance in a different AZ during outages, minimizing downtime and data loss.
- Amazon RDS Proxy efficiently manages database connections, improving scalability and resiliency. It can handle interruptions and reduce failover times by up to 66%.
The other options have limitations:
- Deploying across regions (A) is unnecessary for HA and increases complexity.
- Relying solely on snapshots (C) risks data loss between snapshots and extends recovery time.
- Writing to S3 and using Lambda (D) adds operational complexity without significant HA benefits.
Therefore, leveraging multiple AZs, Multi-AZ database, and RDS Proxy (B) provides high availability with the least operational overhead.
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