How Amazon EC2 Capacity Blocks work - Amazon Elastic Compute Cloud

How Amazon EC2 Capacity Blocks work

You can reserve a Capacity Block with the following specifications:

  • Reserve a start time up to 8 weeks in advance

  • Set a reservation duration of one to 14 days or a multiple of 7 days, up to 182 days (Examples: 21 days, 28 days)

  • Configure up to 64 instances per Capacity Block

  • Configure up to 256 instances across multiple Capacity Blocks

For Amazon EC2 UltraServers, each UltraServer corresponds to one Capacity Block. You can request multiple UltraServers through a single request.

You can use Capacity Blocks to reserve p6-b200, p5, p5e, p5en, p4d, p4de, trn1, and trn2 instances. You can purchase the following UltraServer types through Capacity Blocks: P6e-GB200 and Trn2 (in preview).

To reserve a Capacity Block, you start by specifying your capacity needs, including the instance type or UltraServer type, the number of instances or UltraServers, amount of time, earliest start date, and latest end date that you need. Then, you can see an available Capacity Block offering that meets your specifications. The Capacity Block offering includes details such as start time, Availability Zone, and reservation price. The price of a Capacity Block offering depends on available supply and demand at the time the offering was delivered. After you reserve a Capacity Block, the price doesn't change. For more information, see Capacity Blocks pricing and billing.

When you purchase a Capacity Block offering, your reservation is created for the date and number of instances that you selected. When your Capacity Block reservation begins, you can target instance launches by specifying the reservation ID in your launch requests.

You can use all the instances you reserved until 30 minutes (for instance types) or 60 minutes (for UltraServer type) before the end time of the Capacity Block. With 30 minutes (for instance types) or 60 minutes (for UltraServer types) left in your Capacity Block reservation, we begin terminating any instances that are running in the Capacity Block. We use this time to clean up your instances before delivering the Capacity Block to the next customer. We emit an event through EventBridge 10 minutes before the termination process begins. For more information, see Monitor Capacity Blocks using EventBridge.