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    ApsaraDB RDS:Add or remove a secondary instance

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    ApsaraDB RDS:Add or remove a secondary instance

    Last Updated:Jun 20, 2026

    After you create a Global Active Database (GAD) instance group for RDS for PostgreSQL, you can add a secondary instance to the group by creating a new instance or adding an existing one. If the secondary instance is no longer needed, you can remove it from the group. After being removed, the instance continues to run as a standalone RDS for PostgreSQL instance.

    Prerequisites

    • A Global Active Database (GAD) instance group has been created.

    • The Global Active Database (GAD) instance group is in the Running state.

    • This feature is only available in the following regions: China (Hangzhou), China (Shanghai), China (Beijing), China (Zhangjiakou), China (Shenzhen), China (Hohhot), China (Heyuan), and China (Chengdu).

    Usage notes

    • Adding a secondary instance immediately restarts the primary instance, making it temporarily unavailable. The restart takes approximately 5 to 15 minutes and includes a brief high-availability (HA) interruption that can affect your services for an estimated 10 to 30 seconds.

    • A Global Active Database (GAD) instance group can contain only one primary instance and one secondary instance.

    • An RDS for PostgreSQL instance can join only one Global Active Database (GAD) instance group, either as a primary instance or a secondary instance.

    • While an RDS for PostgreSQL instance is in a Global Active Database (GAD) instance group as a secondary instance, you cannot release the pay-as-you-go instance or cancel the subscription for it. To do so, you must first remove the secondary instance and then manually release the corresponding RDS for PostgreSQL instance.

    Billing

    The cost of Global Active Database includes the fee for a new RDS instance and the fee for Data Transfer Service (DTS) data synchronization. If you add an existing instance as a secondary instance, you are charged for data synchronization but not for the instance. For more information, see Billing of Global Active Database.

    Add a secondary instance

    Warning

    Adding a secondary instance immediately restarts the primary instance, making it temporarily unavailable. The restart takes approximately 5 to 15 minutes and includes a brief high-availability (HA) interruption that can affect your services for an estimated 10 to 30 seconds.

    Create a new instance

    1. Go to the Global Active Database page.

    2. On the Global Active Database page, in the Actions column for the target instance group, click Add Secondary Instance.

      Note

      Alternatively, on the details page of the target GAD instance group, click image.

    3. Configure the new RDS for PostgreSQL instance.

      For other parameters, see Create an RDS for PostgreSQL instance.

      • Billing method: pay-as-you-go or subscription.

      • Major engine version: Same as the primary instance.

      • Instance type:

        • Dedicated: 4 cores and 8 GB of memory or higher.

        • General-purpose: 2 cores and 4 GB of memory or higher.

      • Storage capacity: Greater than or equal to the total storage capacity of the primary instance.

        Note

        You can view the total storage capacity on the Basic Information page of the primary instance, in the Instance Resources section.

    4. Configure the DTS data synchronization link.

      Keep the default settings. No manual configuration is required.

      • Data Synchronization Type: Only One-way Synchronization is supported.

      • Data Synchronization Scope: Only Entire Instance Synchronization is supported.

    5. Review the configuration and billing details for the secondary instance and the DTS synchronization instance. Then, click Pay Now and click OK.

      The system automatically creates a secondary RDS for PostgreSQL instance and a DTS data synchronization link.

    6. After the payment is successful, you are redirected to the details page of the Global Active Database (GAD) instance group. Once the secondary instance is added, you can view it and the DTS synchronization instance on this page. For more information about the page, see View instance group information.

      After the secondary instance is added, the status of each instance in the List of RDS instances and DTS instance list changes to Running.

    Add an existing instance

    The existing RDS for PostgreSQL instance must meet the following requirements:

    • Billing method: pay-as-you-go or subscription.

    • Major engine version: Same as the primary instance.

    • Instance edition: Same as the primary instance. Only Basic Edition or High-availability Edition is supported.

    • Instance type:

      • Dedicated: 4 cores and 8 GB of memory or higher.

      • General-purpose: 2 cores and 4 GB of memory or higher.

    • Storage capacity: Greater than or equal to the total storage capacity of the primary instance.

    Note

    You can view this information on the instance's Basic Information page. If the instance type or storage capacity is insufficient, you can upgrade the configuration. For instructions, see Change instance specifications.

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

    2. In the upper-right corner of the page, click Add to GAD Cluster.

    3. In the dialog box that appears, specify the target Global Active Database instance group.

      Parameter

      Description

      Region

      Select the region where the target Global Active Database (GAD) instance group is located.

      Global Active Database Cluster (Name/ID)

      Select the target Global Active Database (GAD) instance group.

    4. Click OK. You are redirected to the details page of the Global Active Database (GAD) instance group. After the secondary instance is added, you can view it and the DTS synchronization instance on this page. For more information about the page, see View instance group information.

    Remove a secondary instance

    Note

    Removing a secondary instance is different from releasing the instance or canceling its subscription.

    • Removing a secondary instance: This action only removes the secondary instance from the Global Active Database (GAD) instance group. The corresponding RDS for PostgreSQL instance continues to run normally and its data is retained. You can find this instance on the Instances page.

    • Releasing a secondary instance or canceling its subscription: You must first remove the secondary instance before you can release it or cancel its subscription. After an instance is released or its subscription is canceled, the instance is moved to the recycle bin and is permanently deleted after a retention period.

    1. Go to the Global Active Database page.

    2. On the list of Global Active Database (GAD) instance groups, click the ID of the target group.

    3. In the List of RDS instances section at the bottom of the page, find the secondary instance, and in the Actions column, click Remove.

    4. Click Delete.

      Important

      • During the removal process, the corresponding RDS for PostgreSQL instance remains accessible. After removal, it can be added as a new secondary instance to a Global Active Database (GAD) instance group, provided that it meets the requirements.

      • After the secondary instance is removed from the Global Active Database (GAD) instance group, the DTS synchronization link with the primary instance is terminated. It becomes a standalone, read-write (RW) instance.

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