I encountered an error while making the KNOPPIX compressed filesystem from mkisofs. I googled for the answer to why this error was appearing:

end request: I/O error, dev 02:00 (floppy, sector 0)

No one had an answer.

Well, for archival purposes this is what is happening.

At some point you had chrooted to the source, mounted /proc
and did a ^D exit without umount /proc . It left a link in /mnt/floppy
to /mnt/auto/floppy

In the KNOPPIX main system environment there is an auto mounting
reference to the floppy in /etc/fstab , so when you are compressing the source, it hits the floppy drive mount, finds no floppy in your system and produces an error.

The solution: Remove the link to /mnt/auto/floppy in the source area of your KNOPPIX project. I'm not sure if there was a file there before but I suspect it was probably just a directory /mnt/floppy under source.

I removed mine and reran mkisofs without the error appearing again.

In the future, always umount /proc before hitting that ^D ...