AWS Certified Solutions Architect – Associate (SAA-C02) — Question 715

A company's web application is using multiple Linux Amazon EC2 instances and storing data on Amazon Elastic Block Store (Amazon EBS) volumes. The company is looking for a solution to increase the resiliency of the application in case of a failure and to provide storage that complies with atomicity, consistency, isolation, and durability (ACID).
What should a solutions architect do to meet these requirements?

Answer options

• A. Launch the application on EC2 instances in each Availability Zone. Attach EBS volumes to each EC2 instance.
• B. Create an Application Load Balancer with Auto Scaling groups across multiple Availability Zones. Mount an instance store on each EC2 instance.
• C. Create an Application Load Balancer with Auto Scaling groups across multiple Availability Zones. Store data on Amazon Elastic File System (Amazon EFS) and mount a target on each instance.
• D. Create an Application Load Balancer with Auto Scaling groups across multiple Availability Zones. Store data using Amazon S3 One Zone-Infrequent Access (S3 One Zone-IA).

Correct answer: C

Explanation

Amazon EFS provides a shared, POSIX-compliant file system that supports ACID properties and can be concurrently mounted by multiple EC2 instances across different Availability Zones, ensuring high availability and resiliency. EBS volumes (Option A) are limited to a single Availability Zone, while instance stores (Option B) are ephemeral and lose data when instances stop. Amazon S3 One Zone-IA (Option D) is an object storage class restricted to a single zone and does not provide a standard POSIX-compliant file system for EC2 instances.