Question #1159
A solutions architect is designing a cost-optimized architecture for an application that uses Amazon EC2 instances, AWS Fargate, and AWS Lambda. The EC2 instances will handle batch processing workloads, which are irregular and can tolerate interruptions. The backend services on Fargate and event-driven components on Lambda have predictable utilization patterns over the next year. Which combination of purchasing options will provide the MOST cost-effective solution? (Choose two.)
Use Spot Instances for the batch processing layer
Use On-Demand Instances for the batch processing layer
Purchase a 1-year Compute Savings Plan for the backend services and event-driven components
Purchase 1-year All Upfront Reserved Instances for the batch processing layer
Purchase a 1-year EC2 Instance Savings Plan for the backend services and event-driven components
Explanation
The correct answers are A and C.
- A: Spot Instances provide up to 90% cost savings for EC2 workloads that can tolerate interruptions, making them ideal for irregular batch processing.
- C: A Compute Savings Plan applies to Fargate, Lambda, and EC2 usage, offering significant discounts (up to 66%) for predictable, steady-state workloads over 1 year.
Other options are incorrect because:
- B: On-Demand Instances are more expensive than Spot for interrupt-tolerant workloads.
- D: Reserved Instances (RIs) require long-term commitment to specific EC2 instances, which is unsuitable for irregular batch workloads.
- E: EC2 Instance Savings Plans only apply to EC2, not Fargate or Lambda.
Key Points: Use Spot for interrupt-tolerant EC2; use Compute Savings Plans for predictable Fargate/Lambda/EC2 usage.
Answer
The correct answer is: AC