Hi, I'm not familiar with DB/2 but I think the main difference between online backup of DB/2 and online backup of SAP R/3 using TDP is that TDP backs up *ALL* data you would need to restore SAP R/3 in one go. This backup includes database, archive logs and some flat files. With an online DB/2 backup you only get the database.
Another advantage of TDP is that you are using a SAP certified way to backup the system (there might be other). Furthermore you can check the SAP backup within SAP (transaction DB12). We are running SAP R/3 with Oracle on W2K so your mileage might vary. Kind regards Thomas Rupp Vorarlberger Illwerke AG