You want to track changes to database files on your iSeries - who changed them and when?
Turning on journaling would provide the information, but creating usable reports from the output is not easy, and journaling itself is heavy on system resources.
Audit Trail/400 is simple to implement and run, and uses triggers, not journaling - so performance is not a problem. All changes can be tracked, even those made through DFU, SQL or from a PC. Tracked data is output to physical files that can be used within query or your own reports. Audit Trail/400 also helps you comply with FDA regulations.