must the Flash drive be FAT to be bootable?

Question

I used Startup Disk Creator to put an Ubuntu ISO file on a Flash drive FAT formatted. That booted.

I was not able to boot when I used unetbootin (Universal Net Boot Installer) to put the same Ubuntu ISO file on a Flash drive ext4 formatted.

The machine is a Samsung RF711.

Why was there a problem in the latter case?

Solution

No, it is not necessary for the flash drive to be FAT to be bootable but as it stands now most devices are able to recognize natively FAT32 format be it your droid,tv or something else. However you can boot from any format as long as your bootloader recognizes it.

If you are going to use unetbootin then I would recommend using a FAT32 format.

You can also copy a CD image directly to flash drive and make it bootable using dd

dd if=path/to/isofile.iso of=/dev/sdd

Replace /dev/sdd with your flash drive which you can find by,

sudo fdisk -l

Comments

[H2ONaCl]

So what went wrong? I used the Ubuntu Disks utility to format for ext4. Why did that not boot? Why did unetbootin copy the ISO to the Flash drive without any complaint?

[H. Freeze]

unetbootin just extracts files and puts it its own bootloader .....problem is that doesnt work so well with fs type other than FAT32 ...but you can boot from an ext4 formatted partition using bootloader like grub however installing grub to flash drive is a chore. Simplest solution is either use unetbootin on a FAT32 drive or use dd command like i mentioned in my answer.

[SDsolar]

dd does an EXACT COPY of everything. It is not trying to be "smart" like Clonezilla or the other utilities. It simply copies blocks In From one source the Out File - a destination path. /dev/sdd is common for a USB drive of any kind, but it also could be /dev/sdc or /dev/sd2 if there is a second partition so it is very important to do the sudo fdisk -l to see what your system thinks is out there.

[mook765]

@H.Freeze I'd suggest to add a warning as well for the dd-command. A simple typo could destroy the OS or other important data.dd is one of the commands we have to be double careful with. Otherwise correct answer, cheers...