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    Cloud Backup:Cross-zone disaster recovery

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    Cloud Backup:Cross-zone disaster recovery

    Last Updated:May 26, 2026

    ECS disaster recovery (DR) enables cross-zone failover when a production site becomes unavailable due to infrastructure failure. It protects against single-zone outages and helps meet RTO and RPO targets.

    Before you begin

    Before implementation, designate a separate DR zone within the same region and VPC as your production environment. Configure vSwitches for both the replication network and recovery network in the DR zone. These networks can share the same vSwitch.

    Step 1: Create a DR site pair

    To create a cross-zone DR site pair:

    1. Log on to the Cloud Backup console.

    2. In the left-side navigation pane, choose Disaster Recovery > ECS Disaster Recovery. Then click Switch to CDR.

    3. Click Add. In the Create Site Pair panel, set Type to Cross-zone Disaster Recovery and configure Production Site Information and DR Site Information.

    4. Click Create.

    Step 2: Add the servers to be protected

    To add protected ECS instances:

    1. Click the Protected Server tab. In the upper-right corner, select the DR site pair created in Step 1.

    2. On the Protected Server tab, click + Add. Select the ECS instances and click OK. In the Server Status column, the status of the added ECS instances is Agent Installing and then changes to Initialized.

      If the status of an ECS instance is not Initialized, choose More > Server Operation > Restart Server in the Operation column to initialize the instance.

    Step 3: Start replication

    To start real-time replication:

    1. On the Protected Server tab, find the ECS instance that you want to replicate and choose More > Failover > Start Replication in the Operation column.

    2. In the Enable Replication panel, configure the parameters and click Start.

      Parameter

      Description

      Recovery Point Policy

      Select the recovery point creation interval (in hours).

      Hard Disk Type

      Select Ultra Disk, ESSD, or SSD.

      Replication Network

      Select the vSwitch for replicating data from the production zone to the DR zone.

      The list shows available vSwitches from the DR site's VPC.

      Recovery Network

      Select the vSwitch in the DR zone for creating and running ECS instances during failover or drill.

      The list shows available vSwitches from the DR site's VPC.

      Automatic restart after replication interruption

      If selected, replication automatically resumes after an interruption.

      The instance transitions through Enabling Replication, Replicating Full Data, and Replicating states:

      1. Enabling Replication: The service scans data and evaluates total volume. Typically takes a few minutes.

      2. Replicating Full Data: Valid data is replicated to Alibaba Cloud. Duration depends on data volume and network bandwidth. The progress bar in the Server Status column shows replication progress.

      3. Replicating: After full replication completes, Aliyun Replication Service (AReS) monitors disk writes and replicates incremental data in real time.

    (Optional) Perform a DR drill

    After an ECS instance enters the Replicating state, it is ready for a DR drill.

    A DR drill launches a protected ECS instance on the cloud and verifies application functionality. DR drills provide the following benefits:

    • Verify application viability: Confirms that applications run correctly on a restored instance.

    • Improve team readiness: Familiarizes the team with the failover process, enabling a smooth and rapid response during a real disaster.

    To perform a DR drill:

    1. On the Protected Server tab, in the Actions column for the target server, click Test Failover.

    2. In the Test Failover panel, select the Recovery Network, IP Address, whether to Use ECS Specification, Hard Disk Type, Recovery Point, Elastic Public Network IP, and Post Script. Then click Start.

      Note

      • Cloud Backup automatically retains 24 recovery points from the last 24 hours for each server.

      • If not using an ECS instance type, also specify CPU and memory.

      Cloud Backup launches the server in the background from the selected point in time. Real-time data replication continues unaffected during the drill.

      After a few minutes, the drill completes. Click the link under Test Failover Information to verify data and applications.

    3. Clean up the drill environment.

      After verification, in the Actions column for the server, click Cleanup Test Environment. This action deletes the recovered ECS instance.

      Note

      Delete the recovered ECS instance as soon as verification is complete to reduce costs.

    Step 4: Perform a failover

    Regular DR drills verify that applications run successfully on restored ECS instances, confirming that workloads fail over reliably to the DR site during a critical error.

    Warning

    Initiate a failover only for servers that have experienced a critical error. This action stops all real-time data replication. To re-establish protection, restart replication manually, which triggers a new full data replication before continuous protection resumes.

    To perform a failover:

    1. On the Protected Server tab, in the Actions column for the server, choose More > Failover > Failover.

    2. In the Failover panel, select the Recovery Network, IP Address, whether to Use ECS Specification, Hard Disk Type, Recovery Point, Elastic Public Network IP, and Post Script. Then click Start.

      Important

      Recovery to the latest available state is a one-time operation.

    3. After the failover completes, click the link under Recovered Instance ID/Name to verify data and applications.

      • If the application runs correctly at the selected point in time, choose More > Failover > Commit Failover.

        Note

        After completing failover or switching recovery points, and confirming that the recovered application has taken over business traffic, commit the failover to clean up disaster recovery resources and reduce costs.

      • If the application state is unsatisfactory (for example, due to database consistency issues or corrupted source data already synchronized to the other region), before confirming failover, choose More > Failover > Change Recovery Point.

      Note

      Changing the recovery point follows the same process as failover. Select an earlier recovery point.

    Step 5: Perform a failback

    Failback returns operations from the DR site to the original production site after a disaster is resolved. A reverse replication synchronizes data changes from the DR site before the final cutover.

    To perform a failback:

    1. On the Protected Server tab, in the Actions column for the server, choose More > Failback > Reversed Register, then confirm reverse registration of the protected server.

    2. In the Actions column, choose More > Failback > Initiate Reverse Replication.

    3. In the Initiate Reverse Replication panel, select whether to enable Original Machine Recovery, then select the Replication Network and Recovery Network. Then click Start.

      Warning

      Failing back to the original ECS instance is an irreversible action that permanently overwrites all data on the instance. This option is available for both cross-region and cross-zone DR. Proceed with extreme caution.

    4. When the server enters reverse real-time replication, in the Actions column, choose More > Failback > Failback.

    5. In the Failback panel, enter CPU and Memory information, select the Recovery Network and IP, and edit the Execute script after recovery.

    6. After failback completes, in the Actions column, choose More > Failover > Registration to re-register the protected server.