[clug] Recovering old CD-Rs

[Scott Ferguson]

On 18/02/15 12:38, Simon Oxwell wrote:
> Hi all,
> 
> I'm going through a bunch of old CD-R's (some of which would be about 15
> years old) and ripping them to ISO's while I still can, using GNU ddrescue.
> 
> However, I'm having troubles with a couple of disks that obviously have
> something burnt to them, but the CD-ROM (and DVD-ROM) drive isn't
> recognizing them as valid media, as presumably the disk's header has become
> corrupt. Any ideas as to how I might be able to read raw data from these
> CD-Rs?
> 
> 
> Simon
> 

You don't say what the discs are formatted as.

There are three types of problems you're maybe experiencing:-
1. scratched/dirty discs
2. sunlight damage
3. laser read/write is out of alignment

1. Clean your discs with a soft cloth in warm, soapy water. Rinse well
and let them dry. See how much data you can get off them using the
processes in 3, then if you still can't get data off - polish out the
scratches with fine automotive polish or toothpaste (minty air-freshener
in you CD drive). Some people claim success at filling scratches with
MrSheen.

2. You can 'try' setting the drive*s* to the lowest speed and blacking
out the top of the disc with a permanent marker - then try data removal
as per 3.

3. Find out what's on the disc and try the appropriate recovery technique:-
dd if=/dev/sr0 bs=2048k count=1 | file -
OR
isoinfo -d -i /dev/sr0

NOTE: it's worth trying the following methods in several drives
including some older ones that are likely to have a misaligned read laser.

3a. try dvdbackup for movie dvds

3b. for data cd/dvds (and limited success with movie dvds) try a quick
shot at imaging the disc, then try mounting the image.
dd if=/dev/sr0 of=image.iso bs=2048 conv=noerror,notrunc iflag=nonblock
if that fails to produce a useful image try gddrescue, dvdrescue, or
Roadkil's Unstoppable Copier (roadkil.net). If you find partial success
try ddrutility to see whether you're going to miss what you didn't recover.

3c. for data cd/dvds (and limited success with movie dvds) try a long
attempt at imaging the disc, then try mounting the image.

3d. for individual files from data cd/dvds try Foremost and PhotoRec
(TestDisk)

3e. for SVCDs and VCDs try vcdxrip (vcdximager)

3f. unfortunately I can't remember the name of an application I used in
the past which generates a list of unreadable sectors for a disc (though
I've likely got a copy in my archives). It then uses that list to try
and read those sectors on another drive. Rinse and repeat until it gets
all the sectors.
Anyone know the application??


Kind regards