Creating Remote Replication Pairs

By creating a replication pair between a local dtree and remote dtree, you can synchronize data from the local dtree to the remote dtree. If a disaster occurs, you can use the data at the remote end to reconstruct data at the local end. Alternatively, you can directly take over services from the remote end to minimize data loss and shorten service interruption time.

Prerequisites

When creating a remote replication pair, ensure that the secondary dtree has not been used (that is, the dtree must have no data, snapshots, or user-created quotas) and the DPC function of the namespace to which the secondary dtree belongs is disabled. Otherwise, the remote replication pair cannot be created.

Procedure

  1. Choose Data Protection > Protection Entity > Dtree > Remote Replication Pair.
  2. Select a desired account from the Account drop-down list in the upper left corner.
  3. Click Create.

    The Create Remote Replication Pair page is displayed.

  4. Select a namespace for which you want to create remote replication pairs and select dtrees under the namespace from the left. They will be automatically added to the right pane.

    If the cross-site DR feature has been configured for the namespace to which the dtrees belong, you cannot create remote replication pairs for the namespace.

  5. Click Next.
  6. From the Remote Device drop-down list, select the remote device with which you want to create remote replication pairs.
  7. Configure the remote replication pairs.

    1. Click Configure.

      The Configure Pair page is displayed.

    2. Configure the remote replication pairs.
      1. In the Local Resources area, select a local dtree.
      2. Select a remote namespace above the Remote Resources list, and then select a dtree in this namespace from the Remote Resources list.
      3. Click Add to Pair. After the pair is added successfully, the pair will be displayed in the list below.
      4. After pairs are configured for all local resources, click OK.

  8. Set properties of the remote replication pairs. Table 1 describes related parameters.

    Table 1 Remote replication pair parameters

    Parameter

    Description

    Sync Type

    Data synchronization mode of the primary and secondary resources. The value can be:

    • Manual: Data must be manually synchronized between the primary and secondary resources.
    • Timed wait after sync begins: The system starts timing as soon as the latest synchronization begins. After the time specified in Interval is reached, the system automatically starts data synchronization between the primary and secondary resources again.
      NOTE:

      If the last synchronization has not finished after the time specified in Interval is reached, the system performs the next synchronization after the last synchronization finishes.

    • Timed wait after sync ends: The system starts timing after the last synchronization finishes. After the time specified in Interval is reached, the system automatically starts data synchronization between primary and secondary resources again.
    • Specific time policy: The system automatically synchronizes data between the primary and secondary resources based on a specific time policy.

    Interval

    Synchronization interval for Timed wait after sync begins and Timed wait after sync ends.

    [Value range]

    • The value is an integer ranging from 1 to 1440 when minutes is used as the unit.
    • The value is an integer ranging from 30 to 59 when seconds is used as the unit.
    NOTE:

    This parameter is available only when Sync Type is set to Timed wait after sync begins or Timed wait after sync ends.

    Time Policy

    Specific time policy: The system automatically synchronizes data between the primary and secondary resources based on a specific time policy.

    [Value range]

    • Weekly: Data synchronization begins at a specific time on a specific day. Its value ranges from 00:00 Monday to 23:59 Sunday.
    • Daily: Data synchronization begins at a specific time every day. Its value ranges from 00:00 to 23:59.
    • Hourly: Data synchronization begins at a specific minute every hour. Its value is an integer ranging from 0 to 59.
    NOTE:

    This parameter is available only when Sync Type is set to Specific time policy.

    Copy Snapshot Retention in Secondary Resource

    Retention policy of copy snapshots. The value can be:

    • Do not retain: No copy snapshot will be created in the secondary resources after pair synchronization.
    • Retain: The system will create a copy snapshot in each secondary resource each time after pair synchronization to capture the data state of the primary resources at the time when pair synchronization begins.
    NOTE:

    A copy snapshot created under a copy snapshot retention policy in a secondary resource is a replication snapshot. To view such snapshots, choose Data Protection > Protection Entity > Dtree > Snapshot and filter snapshots by Type on DeviceManager.

    Copy Snapshots Retained in Secondary Resource

    Number of copy snapshots retained in the secondary resources. When the number of copy snapshots at the secondary end exceeds the value of this parameter, the system deletes the earliest copy snapshots by default.

    [Value range]

    1 to 512

    NOTE:
    • This parameter is available only when Copy Snapshot Retention in Secondary Resource is set to Retain.
    • The name of a copy snapshot is prefixed by rep_copy.

  9. Set the advanced properties of the remote replication pairs.

    1. Select Advanced in the upper right corner.
    2. Configure advanced remote replication pair properties. Table 2 describes related parameters.
      Table 2 Advanced remote replication pair parameters

      Parameter

      Description

      Speed

      Data synchronization speed of the remote replication pairs. The value ranges from 1 MB/s to 10,240 MB/s (or 1024 KB/s to 10,485,760 KB/s).

      • During initial synchronization, the recommended speed is 100 MB/s or higher.
      • During incremental synchronization, if the service load is heavy, the recommended speed is 0 MB/s to 20 MB/s.
      • During incremental synchronization, if the service load is relatively heavy, the recommended speed is 20 MB/s to 70 MB/s.
      • During incremental synchronization, if the service is idle, the recommended speed is 100 MB/s or higher.
      • The default value is 32 MB/s.

      Recovery Policy

      Whether a remote replication pair automatically synchronizes data after an internal I/O fault or a replication link fault of the remote replication is rectified. The default value is Automatic.

      [Value range]

      • Automatic: The system automatically synchronizes data. The pair enters the Synchronizing state.
      • Manual: Data must be synchronized manually. The pair enters the To be recovered state.

      Initial Sync

      Initial synchronization mode of the local and remote resources. The default value is Automatic.

      [Value range]

      • Automatic: The system automatically synchronizes data of the primary resources to the secondary resources upon pair creation. Ensure that data of the secondary resources is no longer needed or has been backed up.
      • Manual: Data of the primary resources must be manually synchronized to the secondary resources. For details, see Synchronizing a Remote Replication Pair.

  10. Click Next.

    The information summary page is displayed.

  11. Confirm information about the created remote replication pairs and click OK.
  12. Confirm your operation as prompted.
Parent topic: Managing Remote Replication Pairs