On Sat, 18 Aug 2007 14:53:28 +0200, [EMAIL PROTECTED] wrote:
Hi Sebastian,
thanks for taking the time to report this issue!
If I use cdck to verify a CD-R or CD-RW, it reports unreadable sectors
at the end of the disc for several discs which are perfectly
readable (I even verified MD5 sums for one disc).
I'm not sure if this is a bug -- or actually a feature.
cdcd's purpose is not to check for un/readable files but for bad
sectors. From the README:
The known fact is that even if all files on the disc are readable,
some sectors having bad timing can easily turn into unreadable ones
in the future.
In my understanding cdck tries to find problematic factors that
_might_ make sectors unreadable in the _future_, and it warns about
these sectors.
[quoting resorted]
This occured for several discs. The number of bad sectors reported
varies from 14 to 24, but it is always the last sectors.
I also tried a real, pressed CD from retail: The problem did not occur.
I did some tests now with some of my CDs. Results:
* Burnt ISO (bootable, 1 track): bad sectors at the end.
* A random hardware driver CD: no errors.
* Burnt data disc (mutlisession, 5 tracks): bad sectors all around.
Ok, bad example.
* Another burnt iso (bootable, 1 track, rather small): no errors.
* A third burnt iso (bootable, 1 track): bad sectors at the end.
* Another burnt data CD (1 track, rather small): no errors.
* Another random software CD from some vendor (1 track, long but not
full): tons of errors, ok.
* Some random data CD burnt by a vendor (1 track, rather small): no
errors
Hm, I'm not sure what these results actually tell me ...
Maybe cdck incorrectly detects the end of a CD?
I'll check with the upstream author.
Here are excerpted logs for some CDs I tested. They were burnt on
different drives. I also included the volume size as reported by isoinfo
-d (the line Volume size is:). Strangely, it does not agree
with what cdck reports.
That doesn't seem strange to me -- isoinfo checks the size of an iso
file, on the CD there might be more sectors because of the lead in
and lead out. cdck -v shows some info on the structure of the CD.
Cheers,
gregor
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