Writing a Program for Backup and Recovery

There are two methods of creating your own program for backup and recovery:

If you periodically process a data set sequentially, you can easily create a backup copy as a by-product of normal processing. The backup copy can be used like one made by REPRO.
You can write your own program to back up your data sets. Whenever possible, this program should be integrated into the regular processing procedures.
In VSAM, the JRNAD user exit routine is one way to write your own backup program. When you request a record for update, VSAM calls the JRNAD exit routine to copy the record you are going to update, and write it to a different data set. When you return to VSAM, VSAM completes the requested update. If something goes wrong, you have a backup copy. See JRNAD Exit Routine to Journalize Transactions.