Elasticity Assurance offers guaranteed resources to flexibly meet your daily business requirements. If you have consistent resource requirements, we recommend that you use capacity reservations.
Introduction
Elasticity Assurance allows you to pay a small assurance fee for guaranteed access to resources for a fixed period of one month up to five years. When you purchase an elasticity assurance, you must specify attributes such as the zone and instance type. The system uses a private pool to reserve resources that match the specified attributes. For example, you can purchase an elasticity assurance to reserve resources of the ecs.c6.large instance type in Hangzhou Zone I. You can have guaranteed access to the reserved capacity in the private pool to create pay-as-you-go instances.
Elasticity Assurance offers guaranteed resources only to create pay-as-you go instances but not preemptible instances.
An elasticity assurance transitions through the following phases during its lifecycle:
The elasticity assurance is created after you pay for the assurance fee.
You can use the reserved capacity in the private pool associated with the elasticity assurance within the validity period of the elasticity assurance to create pay-as-you-go instances.
The elasticity assurance is automatically released on expiration.
NoteWhen the associated elasticity assurance is released, created pay-as-you-go instances remain unaffected and continue to run as expected. The instances are billed at the pay-as-you-go rate after they are created.
The following figure shows how an elasticity assurance that reserves resources for two pay-as-you-go instances is used.
Benefits
Low-cost guaranteed provision of resources: You can purchase elasticity assurances at low costs to reserve resources for creating pay-as-you-go instances that match the specified attributes over an extended period of time.
Flexibility in resource use time: Elasticity assurances provide guaranteed access to resources and allow you to create and release pay-as-you-go instances within the reserved capacity at any time over an extended period of time.
Use in conjunction with discount plans: Pay-as-you-go instances created from reserved resources in private pools can match existing savings plans or regional reserved instances to benefit from the billing discounts.
Billing
You cannot manually release the elasticity assurances that you purchase. When you use an elasticity assurance, you are charged the following fees:
Assurance fee generated when you create the elasticity assurance
Hourly fees of the pay-as-you-go instances that were created from the reserved resources of the elasticity assurance
NoteYou can apply existing savings plans or regional reserved instances that have matching attributes to offset pay-as-you-go instance fees.
Limits
Elasticity Assurance is available only for specific instance types in specific regions. For more information, see the buy page.
You cannot cancel elasticity assurances or release them before they expire.
Reserved resources in a private pool can be used to create only pay-as-you-go instances that match the instance type and zone attributes that you specified for the associated elasticity assurance.
Zonal reserved instances cannot be used to offset the bills of the pay-as-you-go instances that were created from reserved resources in private pools.
Scenarios
Periodic short-term resource requirements: Elasticity Assurance guarantees the provision of resources when you want to scale your computing resources during a fixed period of time every day, week, or month. If no sufficient resources are available during that period of time, your business is affected. If you require a small amount of resources during the other periods of time and the total resource usage is low, discount plans such as reserved instances are underused. For example, a financial Software as a Service (SaaS) service provider requires a large number of resources to perform an account check at the beginning of each month, or a rendering enterprise needs to process a number of rendering tasks at the beginning of each week.
Occasional large resource requirements: Elasticity Assurance allows you to reserve resources for urgent use. This way, you can have fast access to resources and ensure business continuity when unexpected events occur. For example, Elasticity Assurance is suitable for scenarios in which Internet media companies cover breaking news from time to time or enterprises need to reserve resources for disaster recovery.
Resource guarantee during special periods: In high-traffic periods when resources are strained, such as Double 11 and Spring Festival, Elasticity Assurance helps ensure that key business runs smoothly and avoid risks caused by resource contention. For example, resources required for key business such as live video streaming, ticket-grabbing, and red envelope grabbing need to be guaranteed.
Best practices
A company wants to run key computing tasks while resources are insufficient. In this case, the business of the company may be significantly affected and the following issues may arise:
During the use of preemptible instances, clusters may fail to be scaled out due to insufficient resources in a zone.
Replacing preemptible instances with pay-as-you-go instances for guaranteed provision of resources results in a significant increase in costs.
In high-traffic periods, such as Double 11, pay-as-you-go instances cannot be created because resources are unavailable. As a result, the key business is affected.
Solution:
Plan the required resources and select zones where resources are sufficient.
Purchase zonal reserved instances and elasticity assurances to reduce the costs of pay-as-you-go instances and ensure the provision of resources.
Zonal reserved instances can cover consistently used resources to reduce the costs of pay-as-you-go instances.
Elasticity assurances can be used to meet daily requirements for elastic resources and reserve resources at lower costs than reserved instances do. Elasticity assurances provide guaranteed resources that you can exclusively use to create pay-as-you-go instances even when resources are strained.
You can create pay-as-you-go instances only for key business by using reserved resources in private pools.