Enabling and Purchasing a Reserved Instance

Constraints

• The quota for the number of RIs that you can purchase in the current region is displayed in the upper left area of the Reserved Instance page. The quota for the number of RIs that can be purchased by a user in each region is 20.
• The quota for the number of RIs is automatically reset every month.
• The remaining quota for the number of RIs (Remaining quota = Total quota – Used quota) is reduced only after more RIs are purchased. It will not be changed if RIs are modified, split, combined, or unsubscribed.

Enabling RIs

Before purchasing an RI, contact customer service to apply for the required permissions.

Purchasing an RI

1. Log in to the ECS console and access the ECS list page.
2. In the navigation pane on the left, choose Elastic Cloud Server > Reserved Instance.
3. Click Buy RI.

   The Buy RI page is displayed.

4. Confirm the region.

   If the RIs in the selected region do not meet your requirements, select another region.

5. Set Scope.
   • Regional: Regional RIs (without an AZ specified) do not support capacity reservation. However, they come with instance size flexibility and provide discounts for pay-per-use ECSs with matched instance series and vCPU/memory ratios.
   • Zonal: Zonal RIs support capacity reservation. If you need to purchase RIs that support capacity reservation, select Zonal for Scope.
6. (Optional) Set AZ.

   This parameter is available only when Scope is set to Zonal. You can specify an AZ for the RIs.

7. Select an RI type.

   A range of RI types are provided for you to choose from based on your application scenarios.

8. Filter RI specifications.

   Set the flavor name, OS, term, offering class, and payment option to search for the target RI specifications.

   For details about parameters, see Table 1.

   Table 1 RI attributes

   Parameter	Description
   Region or AZ	Regional RI: indicates an RI purchased in a region, without an AZ specified. Capacity reservations are not supported for regional RIs. Zonal RI: indicates an RI purchased with an AZ specified. Capacity reservations are supported for zonal RIs.
   Flavor Name	When purchasing a regional RI, ensure that the ECS series and vCPU/memory ratio specified in the RI are the same as those of the target pay-per-use ECS. When purchasing a zonal ECS, ensure that the flavor specified in the RI is the same as that of the target pay-per-use ECS. NOTE: After an RI is purchased, its flavor cannot be directly changed, but you can split or combine it. For details, see Modifying RI Attributes.
   OS	The OS of the ECS to be bought, which must match the OS specified in your RI. For example, if you want to use a Linux RI, select a Linux public or private image when purchasing an ECS.
   Term	The service duration of an RI. A year is defined as 31,536,000 seconds (365 days).
   Offering Class	Standard: Certain attributes, such as the instance size, can be modified during the term. However, the instance type cannot be changed.
   Payment Option	No upfront

9. Select specifications.

   A range of RI types are provided for you to choose from based on your application scenarios. On the Buy RI page, view released RI types and specifications.

   • Effective Rate: The hourly unit price of pay-per-use ECSs in the RI term, calculated by dividing the total RI cost by the total hours in the entire RI term. Formula: Effective rate = Total RI cost/Total hours in the RI term
   • Upfront Price: The one-time payment made to purchase an RI
   • Hourly Rate: The hourly costs of pay-per-use ECSs in the RI term, calculated by dividing the difference between the total RI cost and the upfront payment by the total hours in the entire RI term. Formula: Hourly rate = (Total RI cost – Upfront payment)/Total hours in the RI term
10. Specify an RI name.

    The name can be customized. It can contain 1 to 128 characters, which can only be letters, digits, underscores (_), and hyphens (-).

11. Set the number of RIs to be purchased.
    • Quantity: The system displays the number of RIs that you can purchase.
    • Total Normalization Factors: This parameter measures the ECS size flexibility. The value is determined based on the specifications of the RI to be purchased.
    • Total Upfront Price + Pay-per-use Price: The price to be paid for consists of the total upfront price and the pay-per-use price. The total upfront price is the upfront price per RI multiplied by the number of RIs. The pay-per-use price is the pay-per-use price per RI multiplied by the number of RIs.

      For details, click Pricing details.

12. Click Next.

    You can learn more about pricing details here.

13. On the page for you to confirm RI specifications, view details and submit the request.

    After verifying the configurations and price, click Submit and pay for the order as prompted.

14. Return to the RI list as prompted and view the purchased RI.

Follow-up Procedure

• Purchase a pay-per-use ECS that matches an RI.
  Locate the target RI and click Buy ECS in the Operation column. The system automatically switches to the page for purchasing ECSs, and the specifications of the ECSs selected by default are the same as those specified in the RI.

  

  • If the OS of the target ECS does not match the OS specified in the RI, or the target ECS is not billed on a pay-per-use basis, the RI cannot be used. When the attributes of the ECS match those of the RI, including the ECS series and vCPU/memory ratio, the ECS automatically benefits from the billing discount offered by the RI.
• Check the usage of RIs.
  1. On the Reserved Instance page, select the target RI.
  2. Check that the selected RI is displayed at the bottom of the RI list.
     Figure 1 Selected RI
     
  3. Expand the RI details.
     Figure 2 RI details
     
  4. In the RI details area, click View RI Utilization in the RI Usage row to go to Cost Center and view the RI utilization.
     Figure 3 RI utilization