The company has migrated an application to EC2 and will deploy it in an additional Region. The usage is expected to be stable for 3 years, but parts of the application will be redesigned over the next 2 years to use AWS Lambda. Therefore, the company will gradually shift a portion of its compute usage from EC2 to Lambda.
Savings Plans are a flexible pricing model that provide lower prices in exchange for a commitment to a consistent amount of compute usage (measured in dollars per hour) for a 1- or 3-year term. There are two main types of Savings Plans:
• Compute Savings Plans: Apply to any EC2 instance usage regardless of Region, instance family, OS, tenancy, and also apply to AWS Fargate and AWS Lambda usage.
• EC2 Instance Savings Plans: Apply only to a specific instance family in a specific Region.
In this scenario, because there will be a gradual migration from EC2-based compute to Lambda-based compute, a plan that only applies to EC2 (EC2 Instance Savings Plan) risks underutilization as more usage moves to Lambda. Compute Savings Plans, by contrast, can cover EC2 now and Lambda later, maintaining high utilization of the commitment and maximizing effective discount.
Option A recommends evaluating Savings Plans recommendations each year in AWS Cost Management and purchasing a 1-year Compute Savings Plan based on those recommendations. The Cost Management tools and Cost Explorer provide Savings Plans recommendations based on actual usage patterns. Buying 1-year Compute Savings Plans and re-evaluating annually allows the company to adjust its committed spend each year as portions of the application move from EC2 to Lambda. This approach maximizes the chance that the Savings Plans coverage matches the actual combined EC2 and Lambda usage over time and avoids being locked into an EC2-only commitment that becomes increasingly underutilized.
Option B is not optimal because it recommends a 3-year EC2 Instance Savings Plan. That commitment applies only to specific EC2 instance families in a Region and does not apply to Lambda. As the company migrates portions of its workloads to Lambda, the EC2 Instance Savings Plan may become underutilized, reducing the effective discount and potentially increasing overall cost. Compute Optimizer also does not provide Savings Plans purchase recommendations; Savings Plans recommendations come from Cost Management and Cost Explorer.
Option C uses 1-year EC2 Instance Savings Plans and adjusts the commitment each year. While this gives some flexibility, EC2 Instance Savings Plans still do not apply to Lambda usage, so over time there is a risk of underutilizing the EC2 commitment as the Lambda portion grows. This does not maximize savings relative to Compute Savings Plans, which can cover both services.
Option D proposes a 3-year EC2 Instance Savings Plan and suggests decreasing the hourly commitment during the term as workloads move to Lambda. However, Savings Plans commitments cannot be decreased during the term. The company would remain obligated to the original 3-year commitment even if EC2 usage drops, leading to wasted commitment.
Therefore, purchasing 1-year Compute Savings Plans each year based on Savings Plans recommendations from AWS Cost Management (option A) is the best strategy to maximize cost savings while the company transitions part of the workload from EC2 to Lambda.
[References:AWS documentation on Compute Savings Plans and EC2 Instance Savings Plans, including their scope and applicability to EC2, Fargate, and Lambda usage.AWS Cost Management and Cost Explorer documentation describing how Savings Plans recommendations are generated based on historical usage.]
