ApsaraDB RDS:Change the scaling range of RCUs

Feature description

RCUs are a representation of the performance of a serverless ApsaraDB RDS for SQL Server instance. The system automatically adjusts the number of RCUs for a serverless RDS instance within the range that you specified based on your workloads.

The scaling of RCUs for a serverless RDS instance is implemented based on the CPU utilization, memory usage, and average active sessions (AAS) metrics of a serverless RDS instance. If one of the preceding metrics reaches a threshold for a scale-out, the system increase the number of RCUs within a few minutes. If all of the preceding metrics reach the thresholds for a scale-in, the system decreases the number of RCUs within a few minutes.

Scenarios

• Traffic spikes are expected to occur and may affect the load and cause performance jitters. In this case, you can increase the minimum number of RCUs to prevent this issue.

• If you want to reduce costs, you can reduce the maximum number of RCUs. This operation may affect the performance of the serverless RDS instance. Proceed with caution.

Impacts

• The RCU scaling for a serverless RDS instance takes effect within approximately 1 minute.

• The scaling of RCUs causes the following impacts:

  • Change the maximum number of RCUs

    • If the current number of RCUs is smaller than the new maximum number of RCUs, the number of RCUs remains unchanged.

    • If the current number of RCUs is greater than the new maximum number of RCUs, the number of RCUs is immediately decreased to the new maximum number after the configuration takes effect.

    • If the current maximum number of RCUs does not meet your business requirements, the number of RCUs is immediately increased to the new maximum number after the configuration takes effect.

      For example, a traffic spike occurs, the current maximum number of RCUs is 6 and cannot meet your business requirements, and the new maximum number of RCUs is 8. The system immediately increases the number of RCUs to 8 after the configuration takes effect.

  • Change the minimum number of RCUs

    • If the current number of RCUs is greater than the new minimum number of RCUs, the number of RCUs remains unchanged.

    • If the current number of RCUs is smaller than the new minimum number of RCUs, the number of RCUs is immediately increased to the new minimum number after the configuration takes effect.

Billing rules

You are not charged for changing the scaling range of RCUs. The fee for a serverless RDS instance depends on the actual usage of RCUs. For more information, see Pricing of serverless ApsaraDB RDS for SQL Server instances.

Procedure

1. Log on to the ApsaraDB RDS console and go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.

2. In the Configuration Information section of the Basic Information page, click Modify Scaling Settings.

   

3. In the panel that appears, configure the Minimum and Maximum parameters in the RDS Capacity Units (RCUs) section.

   Note

   The minimum value of Minimum is 2. The maximum value of Maximum is 16. You can configure the parameters based on your business requirements.

4. Click OK.

References

• If the storage capacity of your serverless RDS instance no longer meets your business requirements, you can manually expand storage capacity.

• If you do not want to use a serverless RDS instance for a specified period of time, you can stop the RDS instance. For more information, see Stop an ApsaraDB RDS for SQL Server instance and Fees for a serverless RDS instance in different states.

• If you no longer need a serverless RDS instance, you can manually release the RDS instance. For more information, see Release or unsubscribe from an RDS instance.

• In most cases, the RCU scaling can be complete within seconds. In some cases, the RCU scaling may require 3 to 5 minutes to complete due to cross-instance scaling. If you have strict requirements on stability within a specific period of time, you can configure scheduled tasks to adjust the number of RCUs for a serverless RDS instance.

• If you want to change the scaling range of RCUs for a serverless RDS instance by calling an API operation, refer to ModifyDBInstanceSpec.