Question #840
A company operates its application using Amazon EC2 instances and AWS Lambda functions. The EC2 instances maintain a consistent and predictable workload, while the Lambda functions face fluctuating and irregular demand. The application employs an Amazon ElastiCache for Redis cluster as a caching layer.
A solutions architect needs to propose a cost-optimized solution to reduce the company's monthly expenses.
Which solution meets these requirements?
Purchase an EC2 instance Savings Plan for the EC2 instances. Use a Compute Savings Plan for Lambda to cover the baseline usage. Acquire reserved nodes for the ElastiCache for Redis cluster.
Purchase a Compute Savings Plan to cover the EC2 instances. Use Lambda reserved concurrency for the peak Lambda demand. Acquire reserved nodes for the ElastiCache for Redis cluster.
Purchase a Compute Savings Plan to cover all EC2, Lambda, and ElastiCache resources entirely.
Purchase a Compute Savings Plan for the EC2 instances and ElastiCache nodes. Use Lambda reserved concurrency for the expected Lambda workload.
Explanation
The correct answer is A because:
1. EC2 Savings Plans are ideal for consistent EC2 workloads, offering flexibility and cost savings.
2. Compute Savings Plans apply to Lambda's baseline usage (predictable portion), reducing costs while allowing scaling.
3. ElastiCache reserved nodes provide discounts for steady usage.
Why other options are incorrect:
- B: Lambda reserved concurrency guarantees capacity but does not reduce costs; Savings Plans are better for baseline.
- C: Compute Savings Plans do not cover ElastiCache, which requires reserved nodes.
- D: ElastiCache cannot use Compute Savings Plans; reserved nodes are required.
Key Points:
- Use Savings Plans (EC2 or Compute) for predictable compute workloads.
- Use reserved nodes for ElastiCache/Amazon RDS.
- Lambda costs are optimized via Savings Plans (baseline) and pay-per-use (spikes).
Answer
The correct answer is: A