AWS Savings Plan vs Reserved Instances — Comparison

With the AWS Savings plan, users commit to spending a specific price per hour over a fixed period. In return, AWS offers substantial discounts against On-Demand rates for EC2 instances and the Fargate container service. Any consumption above the committed amount is charged at On-Demand rates.

Types of savings plan

1. EC2 savings plan => similar to Reserved instance Standard plan
2. Capacity Savings Plan => similar to Reserved instance Convertible plan
3. Sagemaker Savings plan

Note: Sagemaker savings plan is not covered in this document.

Terms

• 1-year term • 3-year term

Plans

• No upfront
• Partial upfront • Full upfront

Supported Services

• EC2
• Fargate
• Lambda
• Sagemaker

Key Advantages (which is not possible on Reversed Instances )

1. Capacity Savings plans provide the most flexibility regardless of the instance family, size, AZ, and region. Example: You can change from C4 to M5 instances, shift a workload from EU (Ireland) to EU (London) automatically continue to pay the Savings Plan.
   Note: Region restriction is still applied to the EC2 Savings plan
2. Provides the flexibility to move workloads to Lambda and Fargate. Example: You can move a workload from EC2 to Fargate or Lambda at any time and automatically continue to pay the Savings Plan.
   Note: This is not supported by the EC2 savings plan.
3. Provides the flexibility to move workloads to a different OS. Example: You can move from c5.xlarge running Windows to c5.2xlarge running Linux and automatically benefit from the Savings Plan.
   Note: It is supported by both Capacity and EC2 savings plans.

Drawbacks

1. You can’t purchase any savings plan for Elastic Cache, RDS, Redshift, and other services which are not in the supported list.
2. There are no options to resell under-utilized Savings Plans.
3. The discounts aren’t better than Reserved Instances, most of the time, they are the same, and sometimes, they are lower.

When to use a Savings plan.

• If you are using Lambda or Fargate as your workload.
• If you have an unpredictable workload. You can make use of the savings plan recommendations based on the past months.
• If you want more flexible i.e ability to change the AWS Region. You can choose a capacity savings plan.
• Instead of a Reserved instance Convertible plan, you can use a Capacity savings plan

When to use Reserved instance

• If you want a discount for RDS, ElasticCache, or Other AWS Services, Reserved Instance is the only option.
• If your resources are not going to be changing its region, size, etc. Then you can go for the Reserved instance standard plan.

Writer: Mounick

About me: A DevOps engineer and serverless evangelist with a love of all things AWS, innovation, security, software architecture and technolog

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