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Difficulty: EasyPerformance and Scalability Optimization

A company is designing a new session state store for a web application. The session store requires sub-millisecond latency for read and write operations, high availability across multiple Availability Zones, and the ability to persist session data to prevent data loss. Which architecture should the Solutions Architect recommend to meet these requirements?

  1. Deploy an Amazon ElastiCache for Redis cluster with Multi-AZ replication and data persistence enabled.Answer
  2. B
    Deploy an Amazon ElastiCache for Memcached cluster with replication and data persistence enabled.
  3. C
    Deploy a single Amazon RDS for PostgreSQL DB instance with a Multi-AZ deployment configuration, and route the read queries to the standby instance in the secondary Availability Zone.
  4. D
    Deploy an Amazon EC2 Auto Scaling group running local Memcached daemons, and configure the Auto Scaling scale-out cooldown period to 10 seconds to launch instances rapidly as traffic increases.

Answer

Deploy an Amazon ElastiCache for Redis cluster with Multi-AZ replication and data persistence enabled.
An Amazon ElastiCache for Redis cluster with Multi-AZ replication and data persistence enabled provides sub-millisecond response times, automated failover for high availability, and persistent data storage to prevent session loss.

Step-by-Step Solution

1
Analyze the application requirements: sub-millisecond latency, high availability across multiple AZs, and data persistence to prevent session loss.
Identified that the solution must support replication, persistent storage, and memory-speed access.
This establishes the constraints for database/caching selection.
2
Compare caching engines: ElastiCache for Redis vs ElastiCache for Memcached.
ElastiCache for Redis supports both replication (Multi-AZ) and persistence (AOF/RDB), whereas Memcached is purely in-memory and does not support replication.
This rules out Memcached-based solutions.
3
Evaluate the database tier alternatives, such as Amazon RDS for PostgreSQL with Multi-AZ.
RDS Multi-AZ standby instances cannot be read from or written to, and a relational database will not consistently guarantee sub-millisecond latency for session state.
This rules out the RDS standby read strategy.

Key Concept

Selecting high-performance, durable, and highly available caching solutions
Estimated Time:2m 0s
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Topics

Performance and Scalability Optimization

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