Resource Assurance is an service that guarantees the provision of Elastic Compute Service (ECS) resources to meet your changing demands. It allows you to quantify the amount of available resources, reserve resources, plan private pools, and gain a better experience when you query, reserve, purchase, and use resources.

Introduction

The following table describes the services provided by Resource Assurance and their features.
Service Feature Description
Quota Management Elastic Quota Shows quotas on resources such as instance types, images, disks, and security groups, and guarantees the provision of instance resources to some extent.
Resource Reservation
  • Elasticity Assurance
  • Immediate Capacity Reservation
Allow you to reserve resources for different scenarios. An immediate capacity reservation is a capacity reservation that immediately takes effect after it is created. After you purchase an elasticity assurance or immediate capacity reservation, Alibaba Cloud reserves resources that match the attributes of the elasticity assurance or immediate capacity reservation as a private pool.
Private Pool Private Pool Provides guaranteed access to resources for you to create pay-as-you-go instances.

Quota Management

The following table describes the different types of elastic quotas.
Elastic quota type Description
Instance quota Instance quotas are allocated based on zones, instance types, billing methods, and network types. Instance quotas are classified into the following types based on how well the provision of resources is guaranteed:
  • Base quota: specifies the minimum amount of guaranteed instance resources. You can create instances within a base quota with a high success rate. Base quotas are adjusted and allocated before the tenth day of each month based on the usage of your ECS resources. You cannot apply to increase the base quotas.
  • Reserved quota: specifies the amount of instance resources reserved by resource reservations. When you create instances within a reserved quota, you have guaranteed access to the resources that you request. You can create the following resource reservations to increase reserved quotas:
    • Elasticity assurances
    • Immediate capacity reservations
  • Total quota: specifies the maximum amount of instance resources for which access can be guaranteed. A total quota includes a base quota, a reserved quota, and other quotas. The system periodically adjusts your instance quotas based on your instance usage to ensure that growing demands can be met. If a total quota is insufficient for your demands, you can apply to increase it. For more information, see View and increase instance quotas.
Resource quota Resource quotas are quotas on other ECS resources such as images, cloud disks, and security groups. You can apply to increase these quotas. For more information, see View and increase resource quotas.

Resource Reservation

You can purchase elasticity assurances or immediate capacity reservations to reserve resources so that you can have access to the resources when you need them. Different types of resource reservations are suitable for different scenarios.
You can use resource reservations in combination with other instance purchase options such as pay-as-you-go instances, reserved instances, and savings plans, to provision instances. Using a combination of purchase options provides more flexibility than using the subscription instance purchase option alone and can provide guaranteed access to resources that the pay-as-you-go instance purchase option cannot. The following table compares different combinations.
Item Combination of elasticity assurances and pay-as-you-go instances Combination of immediate capacity reservations, savings plans or regional reserved instances, and pay-as-you-go instances
Scenario This combination is applicable to the following scenarios:
  • A financial Software as a Service (SaaS) service provider needs a large number of resources to perform account checks at the beginning of each month.
  • A rendering enterprise needs to process a number of rendering tasks at the beginning of each week.
  • An Internet media enterprise needs to report hot news that appears from time to time.
Resource usage in the preceding scenarios shows discrete spikes over time, as shown in the following figure. spur
This combination is applicable to the following scenarios:
  • An internal office automation (OA) system is used.
  • Resources need to be reserved immediately or over a specified period of time for use with existing regional reserved instances or savings plans.
Resource usage in the preceding scenarios levels out over a period of time, as shown in the following figure. stable
Flexibility in time This combination is flexible about when resources are used. You do not need to plan when to use resources over an extended period of time but purchase resources when you need them. This combination is not flexible about when resources are used. To make resources cost-effective, you must plan when to use them and continuously use them over an extended period of time.
Reserved resources Elasticity assurances reserve resources. Immediate capacity reservations reserve resources.
Billing rule Total price of resources reserved by an elasticity assurance = Assurance fee + Price of created pay-as-you-go instances

If you have purchased regional reserved instances or savings plans, you can apply them to created pay-as-you-go instances.

Total price of resources reserved by an immediate capacity reservation = Price of unused reserved capacity (which is billed at the pay-as-you-go instance rate) + Price of created pay-as-you-go instances
Note During the validity period of an immediate capacity reservation, you are charged for the capacity reservation at the pay-as-you-go instance rate regardless of whether the reserved capacity is used to create pay-as-you-go instances.

If you have purchased regional reserved instances or savings plans, you can apply them to the unused reserved capacity and created pay-as-you-go instances.

Private Pool

Automatically scheduled resources constitute a public pool. All users have access to the resources within the public pool. Instances may fail to be created when resources within the public pool are insufficient. When you purchase a resource reservation, Alibaba Cloud reserves resources that have matching attributes as a private pool for your use to create instances.
Note The capacity in private pools is displayed as reserved quotas to provide an overview of guaranteed resources. For more information about reserved quotas, see View and increase instance quotas.
You can purchase resource reservations based on your planned demands to create private pools to accommodate reserved instances. Then, you can use the reserved resources in the private pools to create instances. You can perform the following private pool-related operations:
  • When you purchase an elasticity assurance or immediate capacity reservation, configure private pool attributes including the following ones:
    • Private pool type: open or targeted private pool. Open private pools are suited to common business that requires guaranteed provision of resources. You can use an open private pool of your choice by specifying its ID or by matching the tags of its associated elasticity assurance or capacity reservation, or use an open private pool selected by the system. Targeted private pools are suited to key business that requires dedicated reserved resources. To use a targeted private pool, you must specify its ID.
    • Tag matching: You can enable tag matching to use open private pools based on tags.

      For example, assume that you have developed a script to create instances with specific tags for your key business. If your key business requires guaranteed provision of resources, purchase an elasticity assurance or immediate capacity reservation. When you purchase the elasticity assurance or immediate capacity reservation, set the private pool type to Open and add the instance tags specified in the script. After the elasticity assurance or immediate capacity reservation is purchased, tag matching is automatically enabled for the associated open private pool. When you run the script to create instances, the associated open private pool is automatically matched and used. This eliminates the need to modify the instance creation script and reduces unnecessary communication and O&M costs.

    For more information, see Purchase an elasticity assurance and Purchase an immediate capacity reservation.

  • When you create instances, you can use one of the following methods to configure which private pool to use:
    • Manually specify the ID of an open or targeted private pool.
    • Manually add tags to use the open private pool associated with an elasticity assurance or capacity reservation that has the tags.
    • Set the private pool type to Open to use an open private pool selected by the system.

    For more information, see Use a private pool to create instances.

The following figure shows the workflow for creating and using private pools. reserve-use-resource
Alibaba Cloud utilizes the capacity of private pools as much as it possibly can.
  • When you purchase elasticity assurances or capacity reservations, Alibaba Cloud takes the instances that you have into account to evaluate whether the current resource inventory can meet your demands.

    For example, assume that you have 100 pay-as-you-go instances and want to release them to create new ones. When you attempt to purchase a capacity reservation to reserve resources, your purchase request is denied due to insufficient resources. You can set the private pool type of your existing instances to Open so that the instances are deemed as matchable resources. Then, you can purchase a capacity reservation.

  • After a private pool is created, it is automatically used by existing instances that match its attributes.
  • If instances no longer match a private pool after instance attributes such as the instance type and operating system are changed, the system checks the instances and matches them to other private pools.
The following section describes some best practices for using private pools:
  • Resources allocated based on business types

    A system administrator creates multiple targeted private pools and informs O&M personnel and developers of different pool IDs. This ensures that different private pools are used to create instances for O&M and development purposes.

  • Resources allocated regardless of business types

    A system administrator creates open private pools. O&M personnel and developers use the reserved resources in the open private pools to create instances. When the reserved resources in the private pools have been used up, resources in the public pool are used.

  • Resources allocated by tag

    A system administrator creates open private pools and adds tags based on business. When you create instances for a specific business, add tags to the instances. The instances automatically match the open private pools that have the same tags.

  • Resources allocated exclusively to a specific business

    A system administrator creates targeted private pools and allows instances to be created only by using these pools for a specific business. When the reserved resources in the private pools have been used up, instances cannot be created.