ApsaraDB RDS:Use the automatic storage expansion feature

Usage notes

• After the storage capacity of your RDS instance is expanded, the storage capacity cannot be automatically reduced. However, you can manually reduce the storage capacity by changing the instance specifications. For more information, see Change the specifications of an ApsaraDB RDS for MySQL instance.

• If your RDS instance is a primary RDS instance and has read-only RDS instances, the system checks the storage capacity of each read-only instance when automatic storage expansion is triggered for the primary RDS instance. If the storage capacity of a read-only RDS instance is less than the required storage capacity of the primary RDS instance after the capacity expansion, the system preferentially expands the storage capacity of the read-only instance. After the system expands the storage capacity of all read-only instances, the system expands the storage capacity of the primary instance.

• If the RDS instance is being backed up, you can start an automatic storage expansion task after the backup is complete.

Billing rules

The billing rules for automatic storage expansion are the same as the billing rules for manual storage expansion of an RDS instance. For more information, see Specification changes.

Procedure

1. 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. Go to the Autonomous Function Management panel.

   • In the left-side navigation pane, choose Autonomy Services > Diagnostics. On the page that appears, click the Autonomy Center tab. On the Autonomy Center tab, click Autonomy Service Settings.

   • In the left-side navigation pane, choose Autonomy Services > Dashboard. On the page that appears, click Autonomy Service Settings.Performance Trends

3. On the Autonomous Function Settings tab, click the Auto Scaling tab. Then, click Add Policy. In the panel that appears, configure the following parameters.

   Parameter	Description
   Policy Name	The name of the policy.
   Mode	The mode of the policy. Select Automatic Storage Expansion.
   Engine Type	The type of the database engine. Only RDS PostgreSQL is supported.
   Specifications	The specifications of the RDS instance. Only Disks is supported.
   Used Storage Space ≥	The threshold that triggers storage capacity expansion. The value equals the percentage of the used storage to the total storage capacity. Valid values: 50% to 90%. Default value: 50%. When the percentage of the used storage of the RDS instance is greater than or equal to the value of the Used Storage Space ≥ parameter, the system automatically expands the storage based on the larger value of the following items: 5 GB 15% of the total storage capacity of the RDS instance For example, if the current storage capacity of your RDS instance is 100 GB, 15% of the current storage capacity is 15 GB, which is larger than 5 GB. Therefore, the storage capacity of the RDS instance is increased by 15 GB when the threshold is reached. After the expansion, the storage capacity of the RDS instance is 115 GB. Note The interval between two storage capacity expansion operations must be at least 10 minutes.
   Maximum Storage	The maximum storage capacity of the RDS instance after automatic storage expansion. The specified value must be greater than or equal to the current total storage capacity of the instance. If the RDS instance uses enhanced SSDs (ESSDs), you can set this parameter to 32,000 GB. If the RDS instance uses standard SSDs, you can set this parameter to 6,000 GB.

4. Click OK.

5. In the Recommended Policies section, click Apply in the Actions column to add a policy to the RDS instance.

   Note

   • To modify a policy, you can click Actions in the Modify column of the policy. In the Update Policy panel, update the policy settings.

   • To cancel the application of a policy to the RDS instance, you can click Applied Policies in the Actions column of the policy in the Cancel section.

View the result of automatic storage expansion

1. On the Autonomy Center tab, select a time range to view the auto scaling events that occurred in the selected time range.Elastic Scaling Events

2. Click Details in the Elastic Scaling Events section to view the details of automatic storage expansion.