ApsaraDB RDS:Use automatic storage expansion

Prerequisites

Before you begin, ensure that you have:

• An ApsaraDB RDS for MySQL instance running MySQL 8.0 or MySQL 5.7

• An instance that uses cloud disks (not local SSDs)

• An Alibaba Cloud account with a sufficient balance to cover expansion costs

• The AliyunServiceRoleForDAS service-linked role (created automatically when you enable the feature if it does not exist)

How automatic storage expansion works

When remaining free storage drops to or below your configured threshold, DAS triggers an expansion. Each expansion adds the larger of:

• 5 GB

• 15% of the current storage capacity, rounded to the nearest multiple of 5

If the storage capacity is less than 50 GB and free storage drops below 10% of total capacity, the minimum expansion size is 10 GB instead of 5 GB.

Example: A 100 GB instance expands by 15 GB (15% of 100 GB), bringing total capacity to 115 GB.

The minimum interval between consecutive expansion events is 10 minutes.

Limitations

• Storage cannot be reduced automatically. After an expansion, reducing capacity requires manually changing the instance specifications. For more information, see Change instance specifications.

• Read-only instances expand first. If your primary instance has read-only instances, DAS checks each read-only instance before expanding the primary. If a read-only instance has less storage than the target capacity of the primary, DAS expands it first. Only after all read-only instances are expanded does the primary instance expand. For more information, see [Product changes/Feature changes] Optimization of automatic storage expansion for ApsaraDB RDS for MySQL instances and ApsaraDB RDS for PostgreSQL instances.

• Billing applies. Automatic storage expansion uses the same billing rules as manual expansion. For details, see Change instance specifications.

Enable automatic storage expansion

1. Go to the Instances page. In the top navigation bar, select the region of your RDS instance. Find the instance and click its ID.

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

3. In the Autonomous Function Management panel, click the Autonomous Function Settings tab and enable the autonomy service.

4. Click the Optimization and Throttling tab, select Automatic Space Expansion, and configure the following parameters.

   Standard SSD is phased out. To increase the storage ceiling, upgrade to ESSD. For more information, see Upgrade the storage type from standard SSDs to ESSDs.

   Parameter	Description
   Available Storage Space	The free-storage threshold that triggers expansion. When free storage falls to or below this value, DAS starts an expansion.
   Maximum Storage of Automatic Expansion	The upper limit for total storage capacity after expansion. Must be greater than or equal to the current storage capacity. Maximum allowed values: ESSD (Enterprise SSD): 32,000 GB; standard SSD: 6,000 GB.

5. Click OK.

6. (Optional) In the Alert Configuration section, configure an alert template and subscribe to alert notifications to track expansion events as they happen. The system recommends a template and adds alert rules for the required autonomy events. Follow the on-screen instructions to complete the configuration.

   1. In the Select Alert Contact Group step, select an alert contact group. For more information, see Manage alert contacts.

      • Click Add Contact to add a contact.

      • Click Create Contact Group to create a new group.

      • To modify or remove a contact, click Edit or Remove in the Actions column.

   2. Confirm the settings in the Associate with Resources step.

   3. Click Submit Configuration and confirm the settings in the dialog box.

   If your instance already has an alert template, add the required autonomy event alert rules to that existing template as prompted. If you need to create a new template, see Configure alert templates. For individual alert rules, see Configure alert rules.

View expansion events

1. Go to the Instances page. In the top navigation bar, select the region of your RDS instance. Find the instance and click its ID.

2. In the left-side navigation pane, choose Autonomy Services > Diagnostics.

3. On the Autonomy Center tab, select a time range and set Type to Auto-Scaling Events.

4. Click Details next to an event to see the full event log.

Related topics

• Reduce storage waste. Enable automatic fragment reclamation to clear tablespace fragments. For more information, see Use the automatic fragment reclamation feature.

• Analyze storage usage. Use storage analysis and capacity assessment to understand how your storage is being used. For more information, see Use the storage analysis feature and Use the capacity assessment feature.

• Other database engines. Automatic storage expansion is also available for PostgreSQL and SQL Server instances:

  • Use the automatic storage expansion feature for an ApsaraDB RDS for PostgreSQL instance

  • Configure automatic storage expansion for an ApsaraDB RDS for SQL Server instance