Package: cdck
Version: 0.7.0-5
Severity: serious
On this machine, cdck gives this verdict for the second of a series of
10 home-made DVDs that contain personal videos:
! TOC and lseek() return different information about size , using
lseek()'s number of sectors which is 2295104
Reading sectors 1-2295104
! unable to read sector 2236433, reason: Input/output error
! unable to read sector 2236434, reason: Input/output error
! unable to read sector 2236435, reason: Input/output error
! unable to read sector 2236436, reason: Input/output error
! unable to read sector 2236437, reason: Input/output error
! unable to read sector 2236438, reason: Input/output error
! unable to read sector 2236439, reason: Input/output error
! unable to read sector 2236440, reason: Input/output error
! unable to read sector 2236441, reason: Input/output error
! unable to read sector 2236442, reason: Input/output error
! unable to read sector 2236443, reason: Input/output error
! unable to read sector 2236444, reason: Input/output error
! unable to read sector 2236445, reason: Input/output error
! unable to read sector 2236446, reason: Input/output error
! unable to read sector 2236447, reason: Input/output error
! unable to read sector 2236448, reason: Input/output error
2295104 ok
CD overall:
Sectors total: 2295104:
Good sectors: 2295088:
Bad sectors (incl. with poor timing): 16
CD timings:
Minimal = 0 usec (0.000000s)
Maximal = 99086095 usec (99.086095s)
Average = 1458 usec (0.001458s)
Conclusion:
Disc contains BAD or even unreadable sectors, put it into trash can!
This install clearly has problems reading optical discs. For a set of
10-15 DVDs which are all (at least) satisfactory according to tests on
another machine, it only gives 7 as satisfactory or better. The rest are
either considered BAD (this one), unstable, or are practically
impossible to verify (I stop the verification after many hours). I know
this machine's problem is not specific to cdck. If its problem is
software, it has to be lower-level, since K3b is also affected. But this
is not a reason to give instructions that can cause data loss.
I'm not very knowledgeable on optical discs, but I see 5 reasons why a
problem could be detected:
1. A software bug (cdck, kernel or other)
2. An issue with the ODD
1. A damaged ODD
2. A dirty ODD
3. An issue with the disk
1. A damaged disc
2. A dirty disc
From these, the disk is only BAD in case 3.1. And even if there are
actually BAD sectors on the disc, that doesn't mean all sectors are bad.
In many cases, discs are the only stores of some data. In these cases,
cdck should instruct to recover the recoverable data and only then to
get rid of the disc. I agree that a damaged disc should in general be
discarded to avoid giving a false impression that the data is available,
but that's a secondary concern. The primary concern with a damaged disc
should be to save the data which it uniquely stores. Putting a disk
right in the trash can just because it has bad sectors is likely to
cause data loss.
--- System information. ---
Architecture: i386
Kernel: Linux 3.2.0-4-amd64
Debian Release: 7.0
990 testing security.debian.org
990 testing debian.mirror.iweb.ca
500 unstable debian.mirror.iweb.ca
1 experimental debian.mirror.iweb.ca
--- Package information. ---
Depends (Version) | Installed
========================-+-=============
libc6 (>= 2.3) | 2.13-37
libgcc1 (>= 1:4.1.1) | 1:4.7.2-5
Package's Recommends field is empty.
Suggests (Version) | Installed
=======================-+-===========
gnuplot |
