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I wonder if it's possible to move a specific EC2 instance that was created as committed use between AWS accounts within organisation?

Here's scenario: suppose that technical company handles IT systems for multiple customers and decided to make use of AWS Organisations to create separate subaccounts for each customer. In most cases systems are running on ECS/EKS clusters so that virtual machines are homogeneous. Because of this homogeneity most of machines are bought with committed use for 1 or 3 years. But at some point customer could leave the company and machines would stay. Would it be possible to move them along with committed use to other subaccount within the same organisation?

Tomasz Kapłoński
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2 Answers2

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The short answer is: yes. Reserved instances can be shared across an organization.

More details can be found here: RIs with consolidated billing

Choose carefully which account makes the RI purchase, so you retain the RI if the child account moves out. See the link above for guidance about how RIs are used across accounts.

Worth adding that a reserved instance (or committed use) is not tied to a specific instance per se. For example. If you had an RI for 1x c5.xlarge and you had 2x c5.xlarges instances deployed, then the RI would attach to the first, if you then terminated that instance it would simply attach to the second.

Alex Moore
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From AWS documentation. More detail can also be found here.

For billing purposes, the consolidated billing feature of AWS Organizations treats all the accounts in the organization as one account. This means that all accounts in the organization can receive the hourly cost benefit of Reserved Instances that are purchased by any other account.

This means you can make the reserved instances in any account and the bill will reflect the discount.

RI Location

Master Account: Putting them all in the master account is effective, and they are not affected by account deletion. You can't choose which account the discount is applied to.

Child account: discount is applied to the account the RI is in, if there are no instances they are applied to that instance type in any other account. If the account is deleted the RI is likely lost and unable to be moved.

Which is best for you depends on your situation, your question doesn't give enough information for me to guide you.

Tim
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  • Well, at the moment we do not have any instances with committed use. In fact we don't have described infrastructure in place but it will happen soon so I am doing research on how to book those machines in a most cost efficient way... – Tomasz Kapłoński Sep 08 '19 at 20:26
  • I think the key question is whether accounts are likely to be removed from the organisation, and if you want the reservation to go with the account or stay with the organisation. – Tim Sep 08 '19 at 21:43