Reserved Instance & Savings Plans (delegated admin'ish) process question.

Question

Drawing on anyones experience with Reserved Instances here, im trying to understand if its possible to have an Account, other than the management Account, which is responsible for purchasing Reserved Instances which are then applied at the payer account level.

AWS say;

*Reserved Instances are first applied to usage within the purchasing account, followed by qualifying usage in any other account in the organization.*

[https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/apply_ri.html#:~:text=Reserved%20Instances%20are%20first%20applied%20to%20usage%20within%20the%20purchasing%20account%2C%20followed%20by%20qualifying%20usage%20in%20any%20other%20account%20in%20the%20organization.]()

This indicates that there can be a purchasing Account which has the ability to query other AWS Accounts resource details, purchase Reserved Instances and they get applied to resources across the Organisation.

AWS also says;

*The pricing benefits of Reserved Instances are shared when the purchasing account is part of a set of accounts billed under one consolidated billing payer account. The instance usage across all member accounts is aggregated in the payer account every month.
This further supports the idea. And assuming the same is applicable for Savings Plans.*

[https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts-reserved-instances-application.html#concepts-reserved-instances-billing:~:text=The%20pricing%20benefits%20of%20Reserved%20Instances%20are%20shared%20when%20the%20purchasing%20account%20is%20part%20of%20a%20set%20of%20accounts%20billed%20under%20one%20consolidated%20billing%20payer%20account.%20The%20instance%20usage%20across%20all%20member%20accounts%20is%20aggregated%20in%20the%20payer%20account%20every%20month.]()

Seems straightforward but wondering, if anyone has experience with Reserved Instances and Savings Plans can comment, if this is at all possible or if any of my thinking is floored? RI's and Savings Plans basically seem to apply to reduce your bill rather than select resources (as they are ephemeral) is my understanding.

twinaws · Answer

Hello,

You can purchase RI's or Savings Plan with a member account. In the example provided, the purchasing account simply means the account used to make the RI/SP purchase. How sharing works is described here:

https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/ri-turn-off.html

Both RI's and SP's are billing discounts, offered in 1 year or 3 year commitment. Generally speaking, purchasing RI's/SP's at the management account level provides the benefit of centralized management and is considered operationally easier to repurchase and report. Use-cases for purchasing at the member account level would for charge back scenarios and when business units need more control.

Hope this helps!

Reserved Instance & Savings Plans (delegated admin'ish) process question.

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