This is a test mode that writes to all the sectors. It will tell you if your disc is good or bad. Only problem is that it takes over 3 hours to test a 50 GB BD-RE. At least it is a program and when it runs you can see the exact spot that the data stops writing if the disc is bad. I used it this way and found that I had a Panasonic 50 GB BD- RE that was bad after about 1:45 into a recording. As I watched it, it started to do re-writes and stopped writing at the bad spot.