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If I burn an iso image with:

wodim -data  dev=/dev/scd0 in.iso

and then read it back out with:

dd if=/dev/scd0 of=out.iso

The resulting files are not identical, out.iso is 2048 bytes shorter then in.iso. What is going on here and how can I fix it?

Using Ubuntu 10.04 and Wodim 1.1.10

PS: dd always ends with an Input/output error, not just with this CD, but with all of them. I think its just a limitation of dd, but an explanation why it happens and how to avoid it would be welcome as well.

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2 Answers

I've had similar problems when burning my CDs with

cdrecord -v -eject dev=/dev/sr0 foo.iso

but it seems it's enough to change the burning mode from the default TAO (track at once) to DAO (disk at once):

cdrecord -v -eject -dao dev=/dev/sr0 foo.iso

To check if the burned CD is identical you can run md5sum:

md5sum /dev/sr0

'-dao' also takes care of the I/O error.

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I use the following with Ubuntu 10.4 to read in a CD that I want to copy or mount virtually:

dd if=/dev/sr0 of=mydisc.iso bs=2048 conv=sync,notrunc

The sync and notrunc make sure that the last few bytes get written. see "man dd" for details

Hotei

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