Savings Plans: EC2 vs. Compute - Application to EC2, Lambda, and Fargate?

EC2 Savings Plans and Compute Savings Plans differ significantly in their application to various AWS compute services. Let's break it down for each service:

Amazon EC2:

• EC2 Instance Savings Plans offer up to 72% savings off On-Demand rates but are limited to a specific EC2 instance family in a chosen AWS Region. They apply regardless of size, OS, or tenancy within that family and Region.
• Compute Savings Plans provide more flexibility, offering up to 66% savings off On-Demand rates. They apply to EC2 usage across any instance family, size, Region, OS, or tenancy.

EC2 Instance Savings Plans are more advantageous if you have stable, predictable usage of a specific instance family in a particular Region. Compute Savings Plans are better if your workloads are more diverse or likely to change over time.

AWS Lambda:

• EC2 Instance Savings Plans do not apply to Lambda functions.
• Compute Savings Plans do apply to Lambda usage, providing significant cost savings.
• There are no specific limitations for Lambda with Compute Savings Plans; they automatically apply to your Lambda usage.

The choice between EC2 and Compute Savings Plans can significantly impact Lambda costs, as only Compute Savings Plans offer discounts for Lambda.

AWS Fargate:

• EC2 Instance Savings Plans do not apply to Fargate tasks and pods.
• Compute Savings Plans do apply to Fargate usage, offering cost savings for containerized workloads.
• There are no specific considerations for containerized workloads with Savings Plans; they apply automatically to your Fargate usage.

As with Lambda, the choice between EC2 and Compute Savings Plans has a noticeable impact on Fargate costs, since only Compute Savings Plans offer discounts for Fargate.

Best practices and guidance:

1. If your workloads are primarily EC2-based and stable within a specific instance family and Region, EC2 Instance Savings Plans may offer the highest savings.
2. For diverse workloads across EC2, Lambda, and Fargate, or if you anticipate changes in your infrastructure, Compute Savings Plans provide the most flexibility and broad application.
3. Use AWS Cost Explorer to analyze your usage patterns and get personalized recommendations for Savings Plans.
4. Consider a mix of both types of Savings Plans if you have both stable EC2 workloads and variable compute needs across services.
5. Remember that Savings Plans require a 1 or 3-year commitment, so factor in your long-term plans when choosing.

By carefully considering your usage patterns across EC2, Lambda, and Fargate, you can select the most cost-effective Savings Plan or combination of plans for your specific needs.
Sources
Savings Plans types - Savings Plans
Compute Savings Plans and Reserved Instances - Savings Plans
What are Savings Plans? - Savings Plans
Services eligible for Savings Plans benefits - Savings Plans