Release 10.1B: Progress Fathom Replication
User Guide


How secondary replication works

Once you use the transition command and the new source database is running and activity is occurring, you can perform secondary replication, as shown in Figure 4–2. Secondary replication is the process of replicating the secondary database back to the primary database.

Figure 4–2: Secondary replication

To perform secondary replication:

  1. Verify that repair is complete on the primary machine and that the machine is running and ready for use.
  2. Perform an online backup of the secondary database:
  3. probkup online db-name device-name 
    

    In which:

    db-name is the name of the secondary database.

    device-name identifies a special device or a standard file.

  4. Move the resultant backup file to the primary machine.
  5. Restore the database on the primary machine in one of the following ways:
    • Use PROREST with the -REPLTransition parameter:
    • prorest -REPLTransition db-name device-name 
      

      In which:

      db-name is the name of the primary database (where you want to restore the backup).

      device-name is the directory pathname of the input device or standard file from which you are restoring the database. (The device name should match the name you specified inStep 2.)

      When the restore completes, the database has been restored on the primary machine as a target database.

    • Use PROREST without the -REPLTransition parameter:
    • Restore the database, as shown:

      prorest db-name device-name 
      

      Transition the database, as shown:

      dsrutil db-name -C transition 
      

      The database is transitioned in accordance with the transition properties for the database. (For information about transition properties, see the "Transition properties" section.)

      When the transition completes, the database is a target database.

  6. Start the database as a target database. The replication agent automatically starts when you start the database.

Once you complete the transition and restart the database, replication resumes from the source database (on the secondary machine) to the target database (on the primary machine). The secondary replication process is essentially Fathom Replication working in reverse: The target database is running on the primary machine, and the source database is running on the secondary machine.

You can now schedule some time to transition the primary database from a target database to a source database, and transition the secondary database from a source database to a target database, completing the failback process.


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