Which solution will provide the MOST cost savings for all the organization’s compute usage?
Purchase Reserved Instances for the organization to match the size and number of the most common EC2 instances from the member accounts.
Purchase a Compute Savings Plan for the organization from the management account by using the recommendation at the management account level.
Purchase Reserved Instances for each member account that had high EC2 usage according to the data from the last 6 months.
Purchase an EC2 Instance Savings Plan for each member account from the management account based on EC2 usage data from the last 6 months.
Explanations:
Purchasing Reserved Instances (RIs) for the organization based on common EC2 instance types may not provide the most cost savings due to their inflexible nature and inability to adapt to unpredictable demand across various accounts. RIs are tied to specific instance types and regions, which can lead to underutilization if workloads change or are unpredictable.
A Compute Savings Plan provides flexibility and cost savings across various compute services (EC2, Fargate, Lambda) and adapts to changing usage patterns. By purchasing at the organization level, it optimizes savings across all accounts and takes advantage of the average usage data over the last 6 months to better match future demands, maximizing cost efficiency.
Purchasing RIs for each member account based solely on past high usage may not be cost-effective, as it doesn’t account for future fluctuations in demand. This approach could lead to overspending if usage decreases or becomes unpredictable in the future, resulting in potential underutilization of RIs.
While an EC2 Instance Savings Plan provides flexibility and can be beneficial, purchasing it separately for each member account might lead to missed opportunities for broader organizational savings. It also limits the benefits to EC2 usage only and does not account for Fargate and Lambda services, which are included in the Compute Savings Plan.
I estimate that the answer is:
Purchase a Compute Savings Plan for the organization from the management account by using the recommendation at the management account level.