Question #847
An online retail company hosts its stateful web-based application and PostgreSQL database in an on-premises data center on a single server. The company wants to scale its operations globally and handle traffic spikes during seasonal promotions. To achieve this, they plan to migrate their application and database to AWS to maximize architectural reliability.
Which solution provides the HIGHEST level of reliability?
Migrate the database to an Amazon RDS PostgreSQL Multi-AZ DB instance. Deploy the application in an Auto Scaling group on Amazon EC2 instances behind an Application Load Balancer. Store sessions in Amazon DynamoDB.
Migrate the database to Amazon Aurora PostgreSQL. Deploy the application in an Auto Scaling group on Amazon EC2 instances behind an Application Load Balancer. Store sessions in an Amazon ElastiCache for Redis replication group.
Migrate the database to Amazon Redshift. Deploy the application in an Auto Scaling group on Amazon EC2 instances behind a Network Load Balancer. Store sessions in Amazon Kinesis Data Streams.
Migrate the database to an Amazon RDS MySQL Multi-AZ DB instance. Deploy the application in an Auto Scaling group on Amazon EC2 instances behind an Application Load Balancer. Store sessions in Amazon ElastiCache for Memcached.
Explanation
Option B is correct because:
1. Amazon Aurora PostgreSQL offers higher availability than RDS Multi-AZ, with automatic storage scaling across 3 AZs and faster failover.
2. Auto Scaling and Application Load Balancer (ALB) ensure the application scales horizontally and distributes traffic efficiently.
3. ElastiCache Redis replication group provides multi-AZ session storage, ensuring high availability and low latency for stateful sessions.
Other options are inferior:
- A: RDS PostgreSQL Multi-AZ is less resilient than Aurora. DynamoDB introduces latency for sessions.
- C: Redshift is unsuitable for OLTP databases. Kinesis isn't designed for session storage.
- D: Migrating to MySQL may require app changes. ElastiCache Memcached lacks replication, risking session loss.
Key Points:
- Aurora offers superior database reliability.
- ElastiCache Redis (replication group) ensures HA session management.
- ALB and Auto Scaling handle traffic spikes effectively.
Answer
The correct answer is: B