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 business. This topic describes how to enable the automatic scale-up feature for an RDS instance.

Prerequisites

  • Your RDS instance runs the RDS High-availability Edition with standard SSDs or enhanced SSDs (ESSDs).
  • DAS is activated for your Alibaba Cloud account. For more information, see Autonomy center.
  • The balance in your Alibaba Cloud account is sufficient for scale-ups.

Billing

The automatic scale-up feature is free of charge. You are charged only for the scale-ups that are triggered. For more information, see Specification change fees.

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. The default observation window is 30 minutes. For more information, see Change the specifications of an ApsaraDB RDS for MySQL instance.

Impacts

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