Originally Posted by H_TeXMeX_H
If the error is near the edge it may be a manufacturing fault or a scratch.
You are right. There was no visible defect, but the best the naked eye will do is about 11 microns, so there could be an affective scratch, and I would not see it.
I now have some BD-RE DL media, and am doing more testing. The drive is pretty much running 24 hours a day with tests.
Here is my working hypothesis: There was a burn artifact, which created a marginal section of the media.
The same, and other media has been written and read multiple times, and I have not been able to reproduce the errors.
I did look at code for md5sum, and cmp. While cmp does a literal comparison, a false positive or negative with md5sum might happen only once in our lifetimes. So for a quick comparison, it is absolutely valid. However, it does not tell you where in a file a difference occurred. For that cmp is definitely desired.
It will probably take me several days for the next round.