IPod as bootable USB

Hi, I have used UNetbootin to put a Linux distribution onto my iPod Nano 4th Generation which I don't use now as I have an iPod Touch. I have erased it and I use it as a USB Drive as it has 8GB of Storage. But whenever I try to boot from it the iPod says connected I tap f9 on startup select USB Hard Disk then there is a flashing line in the top left corner and the iPod automatically ejects itself then nothing happens. Does this mean I can't use it as a bootable USB? Should I go and buy a 8GB USB tommorow? Or could I use a boot loader or something where it doesn't automatically eject...

Thanks.