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ApsaraDB RDS:Configure automatic storage expansion

Last Updated:Oct 08, 2026

Database Autonomy Service (DAS) provides the automatic storage expansion feature for ApsaraDB RDS for SQL Server. This feature monitors the storage of your database instance and automatically expands it when the instance runs low on space to ensure service stability.

Prerequisites

  • This feature is available for ApsaraDB RDS for SQL Server High-availability Edition and Cluster Edition instances.

    Note
    • Automatic storage expansion cannot be configured for individual ApsaraDB RDS for SQL Server read-only instances.

    • For information about automatic storage expansion for other database engines, see the following topics:

  • Ensure that your account has a sufficient balance to pay for the expansion.

  • A service-linked role for DAS is created.

    Note

    If you have not created a service-linked role for DAS, the system automatically creates one before the first automatic space expansion.

Background information

For more information, see DAS Auto Scaling capabilities.

Usage notes

  • When automatic space expansion is triggered for a primary instance with read-only instances, the system first expands any read-only instance whose storage is smaller than the primary instance's target size. Only after expanding all required read-only instances does the system expand the primary instance.

  • Due to Windows driver limitations, this feature is unavailable for some instances. We recommend that you upgrade the minor engine version of SQL Server.

Billing

The billing rules are the same as those for manually upgrading the storage space of an RDS instance. For more information, see Billing rules for configuration changes.

Procedure

  1. Log on to the DAS console.

  2. In the navigation pane on the left, click Intelligent O&M Center > Instance Monitoring .

  3. Find the target instance and click the instance ID to open the instance details page.

  4. In the navigation pane on the left, click Autonomy Center.

  5. On the Autonomy Center page, click Autonomy Service Settings in the upper-right corner.

  6. On the Autonomous Function Management > Autonomous Function Settings tab, turn on the main switch for autonomous services.

  7. On the Optimization and Throttling tab, select Automatic Space Expansion and configure the following parameters.

    Parameter

    Description

    Available Storage Space ≤

    The threshold that triggers an expansion.

    When the available storage space of your instance is less than or equal to this threshold, the system expands the storage by the larger of these two values:

    • 5 GB.

      Note

      If the total storage of the instance is less than 50 GB and the available storage space is less than 10%, the expansion step is 10 GB.

    • 15% of the current total storage of the instance, rounded to the nearest multiple of 5.

    For example, if the current total storage of your instance is 100 GB, 15% of this storage is 15 GB. Because 15 GB is greater than 5 GB, the storage is expanded by 15 GB when the threshold is reached. After the expansion, the total storage becomes 115 GB.

    Maximum Storage of Automatic Expansion

    The maximum total storage for the instance after expansion. This value must be greater than or equal to the instance's current total storage.

    Note

    The minimum interval between two consecutive storage expansions is 10 minutes.

  8. Click OK.

  9. (Optional) Configure an alert template to receive notifications for Automatic Storage Expansion events from your database instance.

    The system recommends an alert template and adds the corresponding alert rules for autonomous events. You can follow the on-screen prompts to complete the configuration.

    Note
    • If you have already configured an alert template for the instance, follow the prompts to add the alert rules for autonomous events to the existing template.

    • If you need to create an alert template and alert rules, see Configure alert templates and Configure alert rules.

    1. Select an Alert Contact Group for notifications.

      • Click Add Contact to add a new alert contact.

      • Click Create Contact Group to create a new alert contact group.

      • Click Modify or Remove next to a contact to modify or delete the contact's information.

      For more information, see Manage alert contacts.

    2. Confirm the Associated Resources.

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

View automatic expansion results

  1. Log on to the DAS console.

  2. In the navigation pane on the left, click Intelligent O&M Center > Instance Monitoring .

  3. Find the target instance and click the instance ID to open the instance details page.

  4. In the navigation pane on the left, click Autonomy Center.

  5. On the Autonomy Center page, view the Auto-Scaling Events for the selected time range.

  6. Click Details to view the details of the automatic space expansion. In the event list, a record named Auto-scaling event with an event level of Notice is displayed. Click the Details button on its right.