I'm looking to create a bootable USB memory stick. However the USB stick has data that I can't afford to delete. If I were to burn an iso image on it the ordinary way, say with Ultraiso, the data will be lost.
My idea is to copy the contents of the bootable iso image directly onto the USB stick, (including the boot loader files), and then make it an "Active" partition, I guess that would solve MBR issue. However that doesn't seem to work.
What am I missing here?
Note that my question is in general here, and not about a particular bootable software.