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Hey everyone. I have been trying to make cd images with dd as k3b says that verson 2.0.3 of cdrecord doesnīt support cd cloning.
My problem is that I have tried to make images for 5 different cds. Slackware 10 d1 and d2 and arch linux 0.6 (All were orignally cd imges downloaded form the net) dd gets to right near the end of the cds and then says:
bash-2.05b$ dd if=/dev/cdrom of=slackd1.iso
dd: reading `/dev/cdrom': Input/output error
1333456+0 records in
1333456+0 records out
Just to test it I tried burning the image for slackware d1 to a cd-rw and it seemed to boot fine.
I also tried copying two other cds with dd windows xp and one of the disks for need for speed underground. dd made images of these cds without any errors.
I also tried installing nero in windows and it coppied the slackware cds without any errors.
It includes a nice script, rawread, that uses the dd command to make dead accurate isos from a cd. You can also check the md5sum of a cd with the rawread script and make sure your generated iso matches the cd md5sum. When I did this, the md5sums of isos generated when I/O errors were encountered never matched the cd md5sum. If no I/O errors were encountered, they always matched.
At any rate, one drive would always screw up with rawread(I/O errors) and one drive was fine. I went into my box and reseated the ide cable to the drive and the I/O errors went away. I came to the conclusion that dd is more touchy than a normal read from the cd drive. Under normal circumstances, a cd drive has a lot or error correction mechanisms and if you get an I/O error, the drive will reread the sector. These mechanisms don't seem to work as well under dd. As a result, dd is much less forgiving of I/O errors. For me, a slight problem with a poorly seated cable went undetected under normal circumstances but was revealed when I used dd.
Bootable cds won't be bootable with isos made from mkisofs. You need a sector by sector exact copy for the cd to be bootable. For a bootable cd, the boot info has to appear on very specific sectors of the cd. This info is lost when you use the mkisofs method you describe. All the data will be there but it won't be on the right sectors thus it won't boot. The dd command preserves the sector location of the data.
Hey kilgoretrout thanks for the info I will check my cables (maby buy some new ones). I think I have tried all three drives though. I have two lg(dvd reader and cd writer) and one nec 2510 dvd-rw(which is supposed to be pretty good)
homey I thought about that but for that kilgoretrout has mentioned (I needed them to be bootable) it wouldnīt work
I've got the same problem. Whenever I try to do a dd or md5sum on a CD (particularly the Slackware 10 set I bought from edmunds-enterprises.com) it'll get most of the way through and then stop with an input/output error. I've tried doing:
Hey DaneM sorry I canīt really help, but just to say I got the EXACT same thing. There were some cds that it seemed like I could make images of all day without errors, but others (Like the slackware cds) always got right to the end and then gave errors.