Lift and shift three Linux VMs to EC2 behind an ALB with shared EFS storage

SAP-C02 By islever Editorial Last updated

Determine the optimal migration approach for existing workloads. Determine a new architecture for existing workloads. Design a strategy to meet reliability requirements.

Short answer

B Migrate to EC2 instances in three Availability Zones with EFS mounted on all of them and an ALB for HTTP routing.

Question

A company has an application that has a web frontend. The application runs in the company's on-premises data center and requires access to file storage for critical data. The application runs on three Linux VMs for redundancy. The architecture includes a load balancer with HTTP request-based routing. The company needs to migrate the application to AWS as quickly as possible. The architecture on AWS must be highly available. Which solution will meet these requirements with the FEWEST changes to the architecture?
  1. Migrate the application to Amazon Elastic Container Service (Amazon ECS) containers that use the Fargate launch type in three Availability Zones. Use Amazon S3 to provide file storage for all three containers. Use a Network Load Balancer to direct traffic to the containers.
  2. Migrate the application to Amazon EC2 instances in three Availability Zones. Use Amazon Elastic File System (Amazon EFS) for file storage. Mount the file storage on all three EC2 instances. Use an Application Load Balancer to direct traffic to the EC2 instances. Correct Answer
  3. Migrate the application to Amazon Elastic Kubernetes Service (Amazon EKS) containers that use the Fargate launch type in three Availability Zones. Use Amazon FSx for Lustre to provide file storage for all three containers. Use a Network Load Balancer to direct traffic to the containers.
  4. Migrate the application to Amazon EC2 instances in three AWS Regions. Use Amazon Elastic Block Store (Amazon EBS) for file storage. Enable Cross-Region Replication (CRR) for all three EC2 instances. Use an Application Load Balancer to direct traffic to the EC2 instances.

Key Takeaways

EFS is the only shared file system in the options that multiple EC2 instances can mount concurrently, and keeping EC2 instances behind an Application Load Balancer preserves the existing HTTP request-based routing model, so nothing in the architecture needs to be redesigned.

An application with a web frontend runs on three Linux VMs for redundancy behind a load balancer doing HTTP request-based routing, and it needs shared file storage for critical data. The company wants to migrate as quickly as possible and the AWS architecture must be highly available.

Common mistake: Reaching for FSx for Lustre with EKS containers, or for S3 with Fargate. EFS is the natural match for a VM-based lift-and-shift with a mounted file system, FSx for Lustre is built for HPC workloads, and S3 is an object store that would require rewriting how the application reads its files, which is the opposite of the fewest changes requirement.

Expert Analysis

Why the Answer Is Correct

The application is a three-node Linux VM tier behind an HTTP-routing load balancer, and the requirement is the fewest architecture changes. Migrating to EC2 instances across three Availability Zones keeps the same compute model, and an Application Load Balancer provides the same layer 7 HTTP request-based routing the existing load balancer performs. Amazon EFS is a shared NFS file system that all three instances mount simultaneously, which directly satisfies the shared file storage for critical data requirement and removes the single point of failure the on-premises design had. Spreading the instances across three Availability Zones delivers the high availability requirement.

Why the Other Options Are Wrong

A: Moving to Fargate containers and S3 changes the compute model and the storage access pattern, so it is not the fewest changes, and S3 has no POSIX mount semantics for an application that expects a file system. C: EKS with FSx for Lustre introduces both a Kubernetes control plane the team must operate and a file system priced and designed for HPC workloads, which is unnecessary for a three-node web application. D: EBS volumes attach to instances only within a single Availability Zone and cannot be attached to the same instance across Regions, so cross-Region replication of an EBS-backed instance is not a valid availability architecture, and it also violates the single-Region scope implied by the ALB.

Community Comment Notes

The community voted 100 to 0 for B, citing the AWS EFS documentation statement that a file system can be used as a common data source for workloads running on multiple instances, and the general reasoning was that EC2 plus EFS plus ALB is a one-to-one mapping of the existing on-premises architecture.

Official Reference

https://docs.aws.amazon.com/efs/latest/ug/what-is-efs.html

This link opens the official vendor documentation in a new tab.

Community Votes

B
100%

100% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 7 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 7

  1. nharaz 👍 4 Answered B
    B - is the best solution to meet the requirements with the fewest changes to the architecture. It maintains the application's architecture by using EC2 instances for compute, EFS for shared file storage across instances (mirroring on-premises file storage capabilities), and an ALB for HTTP request-based routing, ensuring a smooth transition to AWS with high availability.
  2. kejam 👍 3 Answered B
    Answer B: FEWEST changes to the architecture
  3. AzureDP900 👍 2
    Option B meets the requirements with the fewest changes to the architecture: Migrate the application to Amazon EC2 instances in three Availability Zones: This is a straightforward migration of the existing Linux VMs to AWS EC2 instances, which provides high availability and redundancy. Use Amazon Elastic File System (Amazon EFS) for file storage: Amazon EFS is a scalable file system that can be mounted on multiple EC2 instances, providing access to shared files without modifying the application's architecture. Mount the file storage on all three EC2 instances: This ensures that all three EC2 instances have access to the critical data stored in Amazon EFS. Use an Application Load Balancer to direct traffic to the EC2 instances: The existing load balancer with HTTP request-based routing can be replaced with an AWS Application Load Balancer, which provides better performance and scalability.
  4. TonytheTiger 👍 1 Answered B
    Option B - "Amazon EFS provides scalable file storage for use with Amazon EC2. You can use an EFS file system as a common data source for workloads and applications running on multiple instances." https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AmazonEFS.html
  5. alexis123456 👍 4
    Correct Answer is B
Show 2 more comments
  1. HunkyBunky 👍 2 Answered B
    Answer - B
  2. career360guru 👍 1 Answered B
    Option B

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