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    ApsaraDB RDS:Automatic storage expansion

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    ApsaraDB RDS:Automatic storage expansion

    Last Updated:Oct 08, 2026

    Insufficient storage space can lead to write failures, data loss, or even instance crashes, severely impacting your services. Database Autonomy Service (DAS) automatically expands storage when a specified threshold is reached. The expansion process does not require an instance restart and does not affect your workloads.

    Prerequisites

    • Your ApsaraDB RDS for MySQL instance meets the following requirements:

      • Instance version: 8.0 or 5.7

      • Storage type: cloud disk

    • Make sure that your account has a sufficient balance to cover the expansion cost.

    • The service-linked role for DAS has been created.

      Note

      If you have not created the service-linked role for DAS, the system automatically creates it when you enable automatic storage expansion, before the first expansion occurs.

    How it works

    When automatic storage expansion is triggered on a primary instance that has read-only instances, the system checks the storage size of each read-only instance. If a read-only instance has less storage space than the target size of the primary instance after its expansion, the read-only instance is expanded first. After all read-only instances are expanded, the system then expands the primary instance. For more information, see [Product/Feature changes] Optimization of automatic storage expansion rules for ApsaraDB RDS for MySQL and ApsaraDB RDS for PostgreSQL instances.

    Billing

    Billing follows the same rules as manually changing instance specifications. For more information, see Change instance specifications.

    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. In the navigation pane on the left, choose Autonomy Services > Diagnostics > Autonomy Center. On the Autonomy Center page, click Autonomy Service Settings.

    3. On the Autonomous Function Management > Autonomous Function Settings tab, enable the autonomy service.

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

      Parameter

      Description

      Available storage space is less than or equal to

      When your instance's available storage space is less than or equal to the specified threshold, the system expands the storage by the larger of the following values:

      • 5 GB.

        Note

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

      • 15% of the current storage space of the instance (rounded to the nearest multiple of 5).

      For example, if the current total storage space is 100 GB, 15% of this value is 15 GB. Because 15 GB is greater than 5 GB, when the threshold is reached, the system adds 15 GB of storage. After the expansion is successful, the total storage space becomes 115 GB.

      Maximum Storage of Automatic Expansion

      The upper limit of the total storage space of the instance after expansion. This value must be greater than or equal to the current total storage space of the instance.

      • ESSD limit: 32,000 GB

      • standard SSD limit: 6,000 GB

        Note

        The standard SSD is discontinued. We recommend that you upgrade to an ESSD.
      Note

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

    5. Click OK.

    6. (Optional) Configure an alert template to receive alerts and stay informed about Automatic Storage Expansion events for your database instance.

      The system recommends an alert template and adds alert rules for the corresponding autonomy events. Follow the on-screen instructions to complete the configuration.

      Note

      • If you have already configured an alert template for the instance, follow the on-screen instructions to add alert rules for the corresponding autonomy events to the alert template.

      • If you want to create your own 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 add a new alert contact group.

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

        For detailed instructions, see Manage alert contacts.

      2. Confirm the associated resources.

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

    View automatic expansion results

    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. In the navigation pane on the left, choose Autonomy Services > Diagnostics.

    3. On the Autonomy Center tab, select Auto-Scaling Events and a custom time range to view automatic storage expansion details.

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