Modifying Specifications

Scenario

You can modify the specifications of an elastic resource pool to adjust the resource configuration and billing mode based on the actual resource usage requirements of your services. This helps you efficiently use resources and optimize costs.

If the number of CUs of an yearly/monthly elastic resource pool is within the specified range (yearly/monthly CUs), then the resource pool is billed on a yearly/monthly basis. Any excess CUs beyond the specified range (yearly/monthly CUs) are billed by CUH. You can adjust the specifications to make billing more cost-effective based on actual CU usage.

For example, if the current specification for the elastic resource pool (yearly/monthly CUs) is 64 CUs, but most of the time the actual usage exceeds 128 CUs, the 64 CUs will be billed annually/monthly, while the excess 64 CUs will be billed by CUH. To achieve more cost-effective billing, you can change the specification of the elastic resource pool to 128 CUs. Once the specification change is successful, the entire 128 CU range will be billed yearly/monthly, resulting in a more cost-effective billing.

In short, you can change the billing mode of the resources that exceed the specification (yearly/monthly CUs) from pay-per-use to yearly/monthly. This helps you efficiently use resources and optimize costs.

Precautions

• Currently, only yearly/monthly elastic resource pools support specification (yearly/monthly CUs) changes.
• The adjustment of the CU range of a queue, the change of the elastic resource pool specifications, and the CU setting of an elastic resource pool take effect on the next hour.
• You can add queues to adjust the actual CUs of an elastic resource pool. The adjustment takes effect immediately.

Basic Concepts

The specification change of an elastic resource pool depends on the actual CUs of the resource pool.

• Actual CUs: actual size of resources currently allocated to the elastic resource pool (in CUs).
  • When there is no queue in the resource pool, the actual CUs are equal to the minimum CUs when the elastic resource pool is created.
  • When there are queues in the resource pool, the formula for calculating actual CUs is:
    • Actual CUs = max{(min[sum(maximum CUs of queues), maximum CUs of the elastic resource pool]), minimum CUs of the elastic resource pool}.

      For details about the calculation formula, see Actual CUs Calculation Formula.

    • The calculation result must be a multiple of 16 CUs. If it cannot be exactly divided by 16 CUs, round up to the nearest multiple.
  • The actual CUs used by an elastic resource pool are billed as follows:
    • If pay-per-use billing is used, you are billed based on the number of actual CUs. Refer to Elastic Resource Pool Billing Modes.
    • If yearly/monthly billing is used, the specifications are billed on a yearly/monthly basis, and the difference between the actual CUs and the specifications (actual CUs – specifications) is billed on a pay-per-use basis. To achieve more cost-effective billing, you can change the specifications of the elastic resource pool to match the actual CUs. This ensures that all actual CUs are billed on a yearly/monthly basis, resulting in overall cost savings compared to the original method. Detailed instructions can be found in Modifying Elastic Resource Pool Specifications.
  • Scaling out or in an elastic resource pool means adjusting the actual CUs of the resource pool. Refer to Scaling Out or In an Elastic Resource Pool.

• CU range: CU settings mainly control the maximum and minimum CU ranges for elastic resource pool scaling to avoid unlimited resource expansion risks.

  When expanding the specifications of an elastic resource pool, the minimum value of the CU range is linked to the specifications (yearly/monthly CUs) of the elastic resource pool. After changing the specifications of the elastic resource pool, the minimum value of the CU range is modified to match the specifications (yearly/monthly CUs).

• Specifications (yearly/monthly CUs): The minimum value of the CU range selected when purchasing an elastic resource pool is the elastic resource pool specifications. Specifications are unique to yearly/monthly elastic resource pools. The specification part is billed on a yearly/monthly basis, while parts beyond the specifications are billed on a pay-per-use basis.

For more information about basic concepts of elastic resource pools, see Basic Concepts.

Checking Before Specification Change (Expansion)

Before changing the specifications (expansion), check whether the actual CUs are greater than or equal to the target CUs of the new specifications.

If the actual CUs are fewer than the target CUs, you need to increase the maximum CUs of queues or add more queues to adjust the actual CUs.

Example: A yearly/monthly elastic resource pool has 64 actual CUs, a CU range of 64–96, and specifications of 64 CUs. The planned target specification is 80 CUs.

Procedure

1. Increase the actual CUs of the elastic resource pool to 80 by adjusting the maximum CUs of existing queues or adding new queues within the current elastic resource pool.

   When the total maximum CUs of all queues exceeds the actual CUs of the elastic resource pool, the actual CUs will increase. The adjusted actual CUs = min(total maximum CUs of queues, maximum CU limit of the elastic resource pool). (Changes to the CU range of a queue take effect at the next full hour.)

2. Once the actual CUs have been increased to 80, proceed with the specification change operation to update the elastic resource pool's specifications to 80 CUs. (Elastic resource pool specification changes take effect at the next full hour.)

   After the specification change, the minimum CU in the CU range of the elastic resource pool will also align with the actual CUs.

Scaling Out

1. In the navigation pane on the left of the console, choose Resources > Resource Pool.
2. Locate the elastic resource pool you want to scale out, click More in the Operation column, and select Modify Yearly/Monthly CU.
3. On the Modify Yearly/Monthly CU page, set Operation to Scale-out and specify the number of CUs you want to add.
   Figure 1 Scaling out
   
4. Confirm the changes and click OK.
5. Choose Job Management > SQL Jobs to view the status of the SCALE_POOL SQL job.

   If the job status is Scaling, the elastic resource pool is scaling out. Wait until the job status changes to Finished.

Scaling In

By default, the minimum number of CUs is 16. That is, when the specifications of an elastic resource pool are 16 CUs, you cannot scale the pool down.

1. In the navigation pane on the left, choose Resources > Resource Pool.
2. Locate the elastic resource pool you want to scale in, click More in the Operation column, and select Modify Yearly/Monthly CU.
3. On the Modify Yearly/Monthly CU page, set Operation to Scale-in and specify the number of CUs you want to decrease.
   Figure 2 Scaling in
   
4. Confirm the changes and click OK.
5. Choose Job Management > SQL Jobs to view the status of the SCALE_POOL SQL job.

   If the job status is Scaling, the elastic resource pool is scaling in. Wait until the job status changes to Finished.