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Difficulty: EasyPerformance and Scalability Optimization

A company is planning to launch a promotion that will cause an immediate, massive traffic spike (by a factor of 100) to its web application. The application's architecture consists of an Application Load Balancer (ALB), an Auto Scaling group of EC2 instances, and an Amazon RDS for MySQL Multi-AZ DB instance. Which two actions should a solutions architect recommend to optimize performance and ensure the application scales effectively to meet this demand?

  1. Contact AWS Support to pre-warm the Application Load Balancer (ALB) before the event.Answer
  2. B
    Configure the application to route read queries to the standby instance of the RDS Multi-AZ DB instance.
  3. Deploy Amazon RDS Read Replicas and modify the application to direct read traffic to the read replicas.Answer
  4. D
    Rely on the Application Load Balancer's default scaling behavior to handle the traffic spike dynamically.
  5. E
    Configure the Auto Scaling group cooldown period to be shorter than the EC2 instance boot time to accelerate scaling.

Answer

Contacting AWS Support to pre-warm the Application Load Balancer (ALB) and deploying Amazon RDS Read Replicas to offload read traffic are the correct actions to optimize performance and scalability.
Pre-warming the Application Load Balancer ensures it is configured with enough capacity to handle the sudden surge without dropped connections. Creating Amazon RDS Read Replicas allows the database to offload read queries from the primary instance, scaling the database tier horizontally.

Step-by-Step Solution

1
Evaluate the database tier capability to scale reads.
Identify that the standby DB instance in a Multi-AZ deployment cannot serve read traffic, making Read Replicas the correct mechanism for scaling reads.
Ensures read queries are offloaded from the primary writer instance during peak load.
2
Evaluate the load balancer capability to handle flash traffic.
Identify that the Application Load Balancer's default scaling is too slow for an instantaneous 100x spike, requiring manual pre-warming.
Prevents dropped requests and connection timeouts at the entry point of the application.
3
Verify Auto Scaling group configuration to avoid scaling thrashing.
Ensure that the cooldown period is longer than the instance boot and configuration time.
Allows new instances to become healthy and start taking load before the Auto Scaling group decides to scale out further.

Key Concept

Scaling database reads using Read Replicas and managing sudden load balancer traffic spikes via pre-warming.
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Topics

Performance and Scalability Optimization

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