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    Vector Retrieval Service for Milvus:Upgrade a single-AZ instance to multi-AZ disaster recovery

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    Vector Retrieval Service for Milvus:Upgrade a single-AZ instance to multi-AZ disaster recovery

    Last Updated:Jun 22, 2026

    You can upgrade a single-AZ Milvus instance online to an intra-city multi-AZ disaster recovery instance for improved high availability and AZ-level fault tolerance.

    Background

    All components of a single-AZ instance run in one availability zone. If that zone fails, the service becomes unavailable. To improve business continuity, you can upgrade to an intra-city disaster recovery instance, which distributes components across multiple availability zones in the same region for AZ-level fault tolerance.

    Milvus currently supports the following two intra-city disaster recovery modes:

    Mode

    Description

    Resource changes

    Multi-AZ Basic Edition

    Node resources run in a single availability zone. If the primary zone fails, service is restored in a standby AZ. Because node resources are not doubled, this is a cost-effective option.

    The number of node resources does not change. After the primary availability zone fails, nodes with the same number of replicas are immediately launched in the standby AZ.

    Multi-AZ High-availability Edition

    Node resources are deployed with equal replicas in two availability zones, providing real-time hot standby. If the primary AZ fails, failover completes in seconds. This mode is suited for production environments with high availability requirements.

    The number of replicas for all service nodes is doubled, which generates an upgrade order.
    Note

    Currently, you can only upgrade from a single-AZ deployment to either the Multi-AZ Basic Edition or the Multi-AZ High-availability Edition. Direct upgrades from the Multi-AZ Basic Edition to the Multi-AZ High-availability Edition are not yet supported.

    Prerequisites

    • The instance is in the Running state.

    • The instance is a Single-zone Deployment deployment.

    • The target standby AZ is in the same region as the instance.

    • A vSwitch has been created in the target standby AZ within the same VPC as the instance.

    Limitations

    Instances that do not support automatic upgrades

    Some older instances cannot be upgraded from the console due to underlying architecture limitations. To upgrade these instances, submit a ticket for manual assistance.

    Region

    Condition

    China (Zhangjiakou)

    Instances created before December 17, 2025

    China (Hong Kong), China (Beijing)

    Instances created before December 19, 2025

    Germany (Frankfurt), Singapore, China (Ulanqab)

    Instances created before December 23, 2025

    China (Hangzhou), China (Shenzhen), China (Shanghai)

    Instances created before December 25, 2025

    If your instance falls within the preceding scope, submit a ticket to contact technical support.

    Other limits

    • During the upgrade, some queries or writes may time out or fail. We recommend that you perform the upgrade during off-peak hours.

    • If public network access is enabled, it is automatically disabled during the upgrade and re-enabled afterward. Expect a brief interruption to public network access.

    • Upgrading to the Multi-AZ High-availability Edition generates an upgrade order. Make sure that your account balance is sufficient.

    Procedure

    1. Log on to the Milvus console.

    2. In the top navigation bar, select the region where the instance resides.

    3. On the Instances page, find the target instance and click the instance ID to go to the instance details page.

    4. In the Instance Configuration section of the instance details page, click Upgrade next to Deployment Mode.

    5. In the upgrade configuration panel, configure the following parameters:

      Parameter

      Description

      Deployment Model

      Select the target intra-city disaster recovery mode. Valid values: Multi-zone Deployment (Basic) or Multi-zone Deployment (HA).

      Standby AZ vSwitch

      Select a vSwitch in the standby AZ. The vSwitch must be in the same VPC as the instance.

    6. Confirm the configuration and fee changes, and then click OK.

    7. If you select the Multi-AZ High-availability Edition and the instance uses the subscription billing method, complete the payment on the order page.

    After the upgrade, the deployment mode changes to the selected multi-AZ mode. You can view the updated deployment mode on the instance details page.

    Reference