Setting Up Replication Using Automatic Synchronization

The instructions in this section assume that the RDS has been created using the procedure described in Creating a Replicated Data Set. You can synchronize the Secondary using automatic synchronization when the application is active or inactive.

Using the autosync option enables you to automatically synchronize the Secondary data volumes with the Primary data volumes in an RDS and start replication; AutoSync makes the Secondary data volumes up to date with the Primary data volumes. Use this option to synchronize the Secondary when the data volumes contain data and when the application is active or inactive.

Replication to another Secondary can be started only after this automatic synchronization completes. AutoSync copies the data on the Primary to the Secondary over the network using the Data Change Map (DCM). To use AutoSync, each data volume in the RVG must have an associated Data Change Map (DCM).

  To set up replication using automatic synchronization

1. From the Secondary RVG view, choose Replication > Start.
2. In the Replication Options page, select Using Autosync to synchronize the Secondary and start replication using automatic synchronization.
3. Click OK. A message displays the status of your request to start replication.
4. Click Close. The RDS view for hr_rvg on seattle displays the status of replication at this time. At any time, refresh the view to display the current status of replication.

Setting Up Replication Using Full Synchronization

The instructions in this section assume that the RDS has been created using the procedure described in Creating a Replicated Data Set. You can synchronize the Secondary using full synchronization with checkpoint when the application is active or inactive.

  To set up replication using full synchronization

1. From the RDS view or Primary RVG view, choose Tools > Synchronize RVG.
2. Complete the Synchronize RVG dialog box as follows:

   Options: Difference-based synchronization Full synchronization	Select Full synchronization.
   Checkpoint Name	Enter a checkpoint name of your choice. For example, checkpt_presync. The Synchronize RVG task uses this name to create a checkpoint.
   Secondary Host	From the drop-down list, select one or more Secondary hosts to be synchronized. For example, london.
   Display output in reverse order	Select this option to display output in reverse order.

3. Click OK. The status of the synchronization displays. Wait until the synchronization completes before you go to the next step.
4. Click Close when the synchronization completes.
5. From the Secondary RVG view, choose Replication > Start.
6. In the Start Replication dialog box, select Using checkpoint. From the drop-down menu, select the checkpoint name which you entered in step 2. This uses the selected checkpoint to start replication.
7. Click OK. A message displays the status of your request to start replication.
8. Click Close. The Secondary RVG view for hr_rvg on seattle displays the status of replication at this time. At any time, refresh the view to get the current status of replication.

   If you specified multiple Secondary hosts in step 2, repeat step 5 through step 8 to start replication for each Secondary RVG.

Setting Up Replication Using Block-level Backup and Checkpoint

The instructions in this section assume that the RDS has been created using the procedure described in Creating a Replicated Data Set. You can synchronize the Secondary using block-level backup and checkpoint when the application is active or inactive.

  To set up replication using block-level backup and checkpoint

1. From the RDS or RVG view, choose Tools > Start Checkpoint to start a checkpoint on the Primary.
2. In the Start Checkpoint dialog box, enter a name for the checkpoint and click OK. Note down the checkpoint name you entered, for example, checkpt_presync.
3. Perform a block-level backup of the data volumes in the Primary RVG.
4. Choose Tools > End Checkpoint to end the Primary checkpoint when the backup is complete.
5. To confirm that you want to end the checkpoint, click OK.
6. Restore the backup to the Secondary data volumes.
7. When step 6 is completed, check whether the checkpoint you created is still valid by clicking on the checkpoint name in the Primary RVG view. If the checkpoint status shows that it has overflowed, the checkpoint is not valid. Repeat step 1 to step 6.
8. From the Secondary RVG view, choose Replication > Start.
9. In the Start Replication dialog box, select Using Checkpoint. From the drop-down menu, select the checkpoint created above. This uses the selected checkpoint to synchronize the Secondary and start replication.
10. Click OK. A message displays the result of your request to start replication.
11. Click Close. The Secondary RVG view for hr_rvg on seattle displays the current replication status, for the replication that has just been started. At any time, refresh the view to display the current status of replication.
12. In the Primary RVG view, check whether the consistent flag is set on the Primary RLINK. The RLINK becomes consistent only after the data contained in the checkpoint is sent to the Secondary.

    If the Secondary is consistent, the synchronization was successful. If the checkpoint overflows before the Secondary becomes consistent, the synchronization failed. Increase the size of the SRL, and then repeat step 1 to step 11. For instructions on resizing the SRL, refer to the VERITAS Volume Replicator Administrator's Guide.

It is likely that there might be writes beyond the checkpoint that are yet to be sent to the Secondary after the consistent flag is set on the RLINK. In the RDS view, check Status to find out whether the RLINK is up to date.

The same backup and the corresponding checkpoint can be used to set up additional Secondary hosts while the checkpoint is still valid. If a checkpoint has overflowed, its corresponding backup cannot be used to resynchronize the Secondary using that checkpoint. Eventually, any checkpoint becomes STALE and unusable. VRW does not display a warning to indicate if a checkpoint becomes unusable. However, checkpoints that are unusable are displayed in red.