AWS Certified SysOps Administrator – AssociateReliability and Business ContinuityMedium
A company is migrating an on-premises application to AWS. The application uses a monolithic architecture and stores critical state information on local disk, making it difficult to scale and recover from failures. The SysOps Administrator needs to re-architect the application to be highly available and resilient across multiple Availability Zones (AZs) in a single Region, ensuring that state information is not lost during instance failures. Which of the following approaches should the administrator take?
- ADeploy the application on EC2 instances in an Auto Scaling group across multiple AZs and store state in instance store volumes.
- BDeploy the application on EC2 instances in an Auto Scaling group across multiple AZs and store state in Amazon EFS.
- CDeploy the application on EC2 instances in a single AZ and use Amazon S3 for storing state information.
- DDeploy the application on EC2 instances in a single AZ and use Amazon EBS Snapshots for data backup.
Show answer & explanationAnswer & explanation
Correct answer: B. Deploy the application on EC2 instances in an Auto Scaling group across multiple AZs and store state in Amazon EFS.
Deploying EC2 instances in an Auto Scaling group across multiple AZs provides high availability and resilience. Storing state in Amazon EFS ensures that the state data is shared and highly available across AZs and persists independently of individual EC2 instances, allowing new instances to pick up where failed ones left off.
Why the other options are wrong
- A. Instance store volumes are ephemeral; data on them is lost when an instance stops or terminates, making them unsuitable for critical persistent state information.
- C. Single AZ deployment is not highly available. S3 is object storage, suitable for static assets or backups, but not typically for live application state requiring file system semantics.
- D. Single AZ deployment does not provide high availability or resilience against AZ failures. EBS Snapshots are for backup, not real-time shared state across AZs.
Multi-AZ Application with EFS
Deploying an application across multiple Availability Zones with an Auto Scaling group and using Amazon EFS for shared, persistent state ensures high availability and resilience.
- Auto Scaling Group distributes instances across AZs.
- EFS provides shared, highly available, and durable file storage.
- Decouples application state from individual instances.
- Enables seamless instance replacement without data loss.
Memory trick: Spread the servers, share the files, stay alive.