Work with Capacity Reservations - Amazon Elastic Compute Cloud

Work with Capacity Reservations

To start using Capacity Reservations, you create the capacity reservation in the required Availability Zone. Then, you can launch instances into the reserved capacity, view its capacity utilization in real time, and increase or decrease its capacity as needed.

By default, Capacity Reservations automatically match new instances and running instances that have matching attributes (instance type, platform, Availability Zone, and tenancy). This means that any instance with matching attributes automatically runs in the Capacity Reservation. However, you can also target a Capacity Reservation for specific workloads. This enables you to explicitly control which instances are allowed to run in that reserved capacity.

You can specify how the reservation ends. You can choose to cancel the Capacity Reservation or end it automatically at a specified time. If you specify an end time, the Capacity Reservation is canceled within an hour of the specified time. For example, if you specify 5/31/2019, 13:30:55, the Capacity Reservation is guaranteed to end between 13:30:55 and 14:30:55 on 5/31/2019. After a reservation ends, you can no longer target instances to the Capacity Reservation. Instances running in the reserved capacity continue to run uninterrupted. If instances targeting a Capacity Reservation are stopped, you cannot restart them until you remove their Capacity Reservation targeting preference or configure them to target a different Capacity Reservation.