Creating a Synchronous Remote Replication Pair

Prerequisites

• The remote replication license is valid.
• The local and remote storage systems support remote replication.
• The remote volume of a remote replication pair is not mapped to the host.
• The local volume is not configured with features that are mutually exclusive with the remote replication function.
• A replication cluster has been configured and a remote device has been added.
• The remote resource ID has been obtained. To obtain the remote resource ID: Log in to the remote device and choose Resources > Volume. On the page that is displayed, click and select ID, and view the ID of the remote resource whose capacity is the same as that of the local resource.

Procedure

1. Choose Data Protection > Protection Entity > Volume > Remote Replication Pair.
2. Click Create.

   The Create Remote Replication Pair dialog box is displayed on the right.

3. Configure basic information about the remote replication pair. Table 1 describes related parameters.

   Table 1 Remote replication pair parameters

   Parameter	Description
   Replication Mode	Set Replication Mode to Synchronous.
   I/O Timeout Threshold of Secondary Resource	If data on the primary resource fails to be written to the secondary resource after the timeout threshold, the remote replication pair enters the disconnected state.
   Timeout Threshold (second)	The timeout threshold ranges from 15s to 120s. NOTE: This parameter is available only when I/O Timeout Threshold of Secondary Resource is enabled.
   Initial Sync	Mode of initial data synchronization between the primary and secondary resources. Possible values are: Inconsistent primary and secondary resource data. Data is automatically synchronized after pair creation: After a remote replication pair is created, data on the secondary resource is overwritten immediately. Ensure that the data on the secondary resource is no longer necessary or has been backed up. Inconsistent primary and secondary resource data. Manually synchronize data after pair creation: After a remote replication pair is created, manually synchronize data between the primary and secondary resources in a timely manner to ensure data consistency. Consistent primary and secondary resource data. Data synchronization is not required: Ensure that the data on the primary and secondary resources is consistent. If the data is inconsistent, the secondary resource cannot be used to recover data or take over services from the primary resource when the primary resource fails. As a result, data loss and service interruption may occur. This option is not displayed when the resource type is namespace.
   Remote Replication Consistency Group	Consistency group to which the newly created remote replication pair belongs. NOTE: If no remote replication consistency group is available, you can click Create to create a remote replication consistency group and add the remote replication pair to the consistency group.

4. Select the local and remote resources of the remote replication pair.
   1. Select a replication cluster in Local Device and Remote Device respectively.
   2. In the local resource list, select the desired local resource and enter the remote resource ID.
      

      To query the remote resource ID, log in to the remote device, choose Resources > Volume, click , and select the desired volume ID.

   3. Click Sync Parameters and set advanced properties of the remote replication pair. Table 2 describes related parameters. Then click OK.

      Table 2 Remote replication synchronization parameters

      Parameter	Description
      Speed	Data synchronization speed of the remote replication pair. The value ranges from 1 MB/s to 1024 MB/s (or 1024 KB/s to 1,048,576 KB/s). During initial synchronization, the recommended rate is 100 MB/s or higher. During incremental synchronization, if the service load is heavy, the recommended rate is 0 MB/s to 20 MB/s. During incremental synchronization, if the service load is relatively heavy, the recommended rate is 20 MB/s to 70 MB/s. During incremental synchronization, if the service is idle, the recommended rate is 100 MB/s or higher. The default value is 32 MB/s.
      Recovery Policy	Whether the system automatically synchronizes data after a remote replication fault is rectified. The default value is Automatic. [Value range] Automatic: The previous ongoing tasks automatically resume immediately after the remote replication fault is rectified. Manual: The value of Running Status changes to To be recovered after the remote replication fault is rectified. In this case, you can check the system and then determine whether to resume the previous ongoing tasks manually.

5. Click OK.