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Elastic Compute Service:Use a private pool to create ECS instances

Last Updated:Jul 09, 2025

After you purchase a resource reservation, Alibaba Cloud reserves resources that match the attributes of the resource reservation in a private pool. You can use these reserved resources to create instances. This topic describes how to use a private pool to create Elastic Compute Service (ECS) instances.

Important

When you release a reserved bare metal instance, the capacity it occupies in the private pool takes a long time to become available again. During this period, attempts to create new instances using this capacity might fail. You need to plan the release time and frequency of instances carefully.

Prerequisites

Procedure

Console method

This section describes only the private pool-related parameters involved in creating ECS instances. For information about other parameters, see Create an instance on the Custom Launch tab.

  1. To use a private pool to create ECS instances in the ECS console, use one of the following methods to access the ECS instance buy page:

    • On the Instance page, click Create Instance.

      image

    • On the Resource Reservations page, find a resource reservation in the Active state and click Purchase Instance in the Actions column.

      image

  2. Configure the basic settings.

    On the Custom Launch page, pay attention to the parameters described in the following table.

    Parameter

    Description

    Billing Method

    • To use the private pool that is associated with an elasticity assurance, an immediate capacity reservation, or a capacity reservation with Savings Plan, set this parameter to Pay-as-you-go.

    • To use the private pool that is associated with a capacity reservation for subscription resources, set this parameter to Subscription.

    Region

    Select the same region as the resource reservation.

    Network And Zone

    Select the same network and zone as the resource reservation.

    Instance

    Select the same instance type as the resource reservation.

    Image

    To use the private pool that is associated with an immediate capacity reservation, select an image that uses the Linux or Windows operating system that is the same operating system used by the immediate capacity reservation.

  3. Configure the parameters in the Storage, Bandwidths & Security Groups, and Management sections. Then, click Advanced Settings(Optional).

  4. In the Advanced Settings(Optional) section, configure the parameters based on your business requirements. In the Private Pool Type field, specify whether to use a private pool and how to use it. You can configure the following options:

    • Specify the ID of a private pool: When creating instances, select Targeted from the Private Pool Type drop-down list and specify the ID of the private pool you want to use. The ID of a private pool is the same as the ID of the associated resource reservation. If the specified private pool has no available capacity, instances cannot be created.

      Note

      You can specify the ID of either an open private pool or a targeted private pool.

    • Use an open private pool assigned by the system: If you select Open from the Private Pool Type drop-down list, the system automatically selects an open private pool. If the open private pool does not have available capacity, the system attempts to use capacity from a public pool.

      Note

      The system selects only open private pools.

    • Specify not to use private pool capacity: When creating instances, select None from the Private Pool Type drop-down list. The public pool will be used.

  5. Review your configurations, read the terms of service, confirm to create the instance, and complete the payment.

OpenAPI method

When you call the RunInstances operation to create an ECS instance, configure the PrivatePoolOptions.MatchCriteria parameter to specify the private pool type of the instance.

  • Open: open private pool. The system selects a matching open private pool for instance startup. If no matching open private pools exist, the system uses resources in the public pool to start the instance. If you set the parameter to Open, you can leave the PrivatePoolOptions.Id parameter empty.

  • Target: targeted private pool. The system uses the capacity in a specified private pool to create instances. If the specified private pool is unavailable, the instances cannot be created. If you set the parameter to Target, you must specify the PrivatePoolOptions.Id parameter.

  • None: no private pool. The system does not use capacity in private pools.

What to do next

After you use a private pool to create instances, you can verify which instances are created and associated with the private pool on the Private Pools tab. For more information, see View a private pool and the instances that are using the private pool.