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I would like to understand the following:

I have a Debian installation CD that I can boot from. Now I copied that to an USB-stick using dd

dd if=/dev/sr0 of=/dev/sdc bs=1M

The CD-image should contain a boot-sector and everything else that is needed for booting, yet the USB stick does not boot.

What am I missing – why does the stick not boot?

PS: I am not interested in tips on how to create a bootable stick, I only want to understand why the above method does not work.

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Because they use different file system and boot information format? You must copy the files (using normal file copy) and boot info separately. –  billc.cn Aug 15 '11 at 23:11
    
@billc.cn What is that supposed to mean? Could you please elaborate - sorry but I don't understand your comment. –  morgon Aug 15 '11 at 23:31
    
CDs normally use CDFS (ISO 9660) or UDF as their file system and these should not normally be used on a USB stick. The boot information also needs to be presented in a different format (e.g. MBR) for BIOS to be able to boot from it. –  billc.cn Aug 16 '11 at 0:44

2 Answers 2

I don't know about the specifics of El Torito, but I don't believe "boot sectors" work the same way on a CD.

Does El Torito (the CD boot standard) specify what the first sector should contain? If not, then there's probably garbage in the first sector, making it unbootable.

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Whenever I've done it, I've used the path of the USB device itself, not the first partition. That is, /dev/sdc rather than /dev/sdc1.

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