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If I:

dd if=/dev/cdrom of=cdrom.iso

then I will always get the exact same, bit-by-bitly same image that is the same as the original CDROM?

Or are there any methods that prevents copying all the bits from the CDROM? Asking for archiving old games on old CDROMS

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up vote 10 down vote accepted

No, dd can be not sufficient. As examples:

  1. If you have a multi-track cd-rom with data and audio track mixed, using dd you will copy only the first data session.
  2. Many old video-games cd (on Play-Station 1) use as copy-protection some fake session on the cd. You have to replicate them to obtain a working cd.

I successfully used cdparanoia to backup quite all my old game cds.

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how do I know that there is copy-protection? dd fails to copy? if the sha256sum of the /dev/cdrom matches the dd'ed iso file's sha256sum then it's 100% that it's ok, no? – LanceBaynes Sep 24 '11 at 9:41

Yes, you should. Under Linux, you can even mount this ISO as if it were a real CD by using the -o loop option to mount. Under Windows, though, you'd need a special software program to emulate a CD drive.

However, this is assuming that the dd doesn't return any errors such as dd: reading '/dev/sr0': Input/output error, as happens when I try to back up some DVDs of mine.

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