The automatic scale-up feature of Database Autonomy Service (DAS) can automatically scale up your ApsaraDB RDS for MySQL instance based on your workloads to handle traffic spikes and ensure the stability of your RDS instance.

Prerequisites

  • Your RDS instance runs RDS High-availability Edition with standard SSDs or enhanced SSDs (ESSDs).
    Note The automatic scale-up feature is not supported for RDS instances whose instance types are phased out. If the instance type of your RDS instance is phased out, you must change the instance type of the instance before you can enable the automatic scale-up feature. For more information about how to change the instance type of an RDS instance, see Change the specifications of an ApsaraDB RDS for MySQL instance.
  • DAS is activated within your Alibaba Cloud account. For more information, see Autonomy center.
  • The balance in your Alibaba Cloud account is sufficient for scale-ups.

Billing rules

By default, the automatic scale-up feature is disabled and does not produce fees. If you enable the automatic scale-up feature, you are charged based on the new instance type that is selected during the automatic scale-up. The price for a scale-up varies based on the instance configuration, such as the region and the new instance type. For more information, visit the ApsaraDB RDS buy page.

Automatic scale-up process

Flowchart
After you enable the automatic scale-up feature for your RDS instance, DAS scales up the RDS instance based on the loads on the RDS instance if the average CPU utilization of the RDS instance over the specified observation window reaches the specified threshold. The specifications of your RDS instance after a scale-up cannot exceed the specifications that are specified by the Upper Limit of Specifications parameter. You can specify this parameter in the ApsaraDB RDS console. After your RDS instance is scaled up, DAS continues to monitor the CPU utilization of the RDS instance. If the CPU utilization over the specified observation window reaches the specified threshold again, DAS scales up your RDS instance again. This process continues until the specifications of your RDS instance reach the maximum specifications that are specified by the Upper Limit of Specifications parameter.
Note After your RDS instance is scaled up, the RDS instance cannot be automatically scaled down. You can subscribe to scale-down suggestions and manually change the specifications of your RDS instance based on the scale-down suggestions. For more information, see Event subscription. If the average CPU utilization of your RDS instance remains lower than 30% over the specified Observation Window, ApsaraDB RDS pushes scale-down suggestions to you. You can manually change the specifications of your RDS instance based on the scale-down suggestions. For more information, see Change the specifications of an ApsaraDB RDS for MySQL instance.

Impacts

  • When the new specifications are being applied to an RDS instance, a transient connection that lasts approximately 30 seconds may occur. Make sure that your application is configured to automatically reconnect to the RDS instance.
  • If an RDS instance does not run the latest minor engine version, DAS updates the minor engine version of the RDS instance to the latest version during a specification change. This ensures the performance and stability of the RDS instance.
  • After you enable the automatic scale-up feature for an RDS instance, ApsaraDB RDS assigns the AliyunServiceRoleForDAS service-linked role to DAS. This way, DAS can access the resources that are related to ApsaraDB RDS.

Procedure

  1. Visit the RDS instance list, select a region above, and click the target instance ID.
  2. In the Configuration Information section of the page that appears, click Settings to the right of Automatic Scale-up.
  3. In the dialog box that appears, configure the following parameters.
    Parameter Description
    Automatic Resource Elasticity Specify whether to enable the automatic scale-up feature.
    Observation Window Select the time range during which you want to observe the CPU utilization of the RDS instance. Valid values:
    • 20 minutes
    • 30 minutes
    • 40 minutes
    • 60 minutes
    Note DAS periodically checks the CPU utilization of the RDS instance during the selected time range. If the CPU utilization reaches the value of the CPU Trigger Threshold parameter, an automatic scale-up is triggered.
    CPU Trigger Threshold Specify the average CPU utilization threshold based on which DAS scales up the RDS instance. Unit: percent (%). Valid values: 50 to 90. You can adjust the threshold at a step size of 10%.
    Upper Limit of Specifications Select the maximum specifications that are supported by the automatic scale-up feature.
    Note If the average CPU utilization of the RDS instance reaches the value of the CPU Trigger Threshold parameter over the specified observation window, DAS scales up your RDS instance based on your business requirements. If the average CPU utilization of the RDS instance reaches the value of the CPU Trigger Threshold parameter again over the specified observation window, DAS scales up the RDS instance again. This process continues until the specifications of the RDS instance reach the maximum specifications that are allowed.
  4. Click OK.
    In the Configuration Information section of the page, the status of Automatic Scale-up changes to Enabled.