Excepting certain media / drive incompatibilities, any media written on any drive should read in any other drive, preferably at full speed.
Whenever I have a piece of media the quality of which is in serious question, I don’t bother with a Disc Quality scan, instead I go right to the TRT and ScanDisc tests. I have found that both add pieces to the puzzle.
With a TRT, a disc can have to slow down due to bad condition, still read the data and “pass” the test, but the graph will show you that the disc needs to be copied and then tossed. I once threw out a disc on the basis of a dodgy TRT result even though PI rates were not insane. This was back when my Sammy started coastering discs (and so I only use it for reading).
If I am not mistaken, the ScanDisc test does something similar, it does a Read Test, which adds another piece to the puzzle. I think that it attempts to read all sectors, showing green for perfect sectors, red for destroyed ones, and, most usefully, yellow sectors where lost bits can be corrected by the error correcting layer. (with CDs for example, 14 bits are used to represent every byte, leaving a redundancy and correction margin of 6 bits per octet). Besides if you’re watching the test unfold, you can see how fast its able to read (it tells you how fast its reading in the lower right corner), which gives you most of the benefits of a TRT.
I am most likely to toss a disc firstly based on the results of a ScanDisc test, secondly by a TRT. I would never toss a disc based soely on a Quality Scan, unless the results were crazily out of line with my expectations.
Therefore, a TRT and a ScanDisc both provide useful clues. A disc could pass a TRT at full speed but still have damaged sectors that you would only see in a ScanDisc test. But the TRT gives you a nice graph so you can review read speeds at the end.
I only use Quality Scans when I’m expecting an extreme result - when with Verbs, I expect uber-low PI rates or when a disc is unreadable (like some paper labelled discs I was unfortunate enough to recieve from friends and nooby-ass media distributors) to see just how correspondingly awful the C2/PI rates are as an indication of how bad the disc really is.
I would therefore recommend to anyone the following:
- If you’re prepared to sit and watch the test, do a ScanDisc test to check for data and error margin integrity, while you’re watching it you will get most of the benefits of a TRT. I.E. if the drive has to slow down to read the disc, you’ll know about it.
- If you need/want to do ScanDisc tests unattended, do a TRT separately.
- DQ scans can only really be used for more detailed examination of a disc once the other two tests given the all-clear. The lack of CU/PO Failure reporting in modern optical drives makes serious integrity checking via a Quality Scan next to impossible.