How should I set up my flash drive for multi-boot?

I stopped at the BuyMore yesterday and bought a 32GB USB 3.0 flash drive, the smallest size available.

I’ve downloaded all the distros that interest me : Elementary, Ubuntu, Mint, and Manjaro. If you’re around me long enough, you’ll find that “phone home” software is a giant red flag for me, so instead of Etcher I’ve grabbed USBImager. This will hopefully all come together in a bootable flash for my 2012 iMac.

There’s plenty of advice about a dual-boot USB for Mac. What I would like to do is a multi-boot USB flash drive. I’d like to be able to alt-boot the iMac to a menu that gives me a choice between the 4 distros. The total footprint of my Linux distros plus USBImager is around 12GB - should I partition half the USB flash drive into OS and half for data, and then drop all the distros into that partition? Or should I do a different partition for each distro, and maybe one more for data?

A couple years ago I built a bootable USB using Etcher to set up Elementary. I didn’t take notes and I can’t remember how I did it. I had to wipe Elementary and go back to MacOS on that machine, as it was needed in my office, so I never had a chance to enjoy the install other than a little exploration of the GUI. Once I have this figured out I’ll be exploring Linux for real.


Hey @MarkLX
Honestly, I wouldn’t recommend putting four different distros on one flash drive. It could confuse your machine’s BIOS and cause problems. You’d probably be better off flashing one at a time.

Hey @MarkLX!
What @SBHX said is very correct. I would also add that it’s impossible to make a multi boot USB for the following reason:
When you flash an ISO onto a USB stick, it copies the contents of the ISO sector-by-sector. This includes the boot blocks. Every ISO you flash, it will overwrite those blocks.

Additionally, the boot block in the FAT32 system (which is used to boot - as a small partition) has a hardware/filesystem limitation. Once you surpass sector 1024 of the device, there can be no more boot blocks. And the fact that the boot partition is usually 512MB to 1GB, already surpasses that limitation.

Thus, if you want to have multiple bootable distro USBs, you will need the respective number of devices.

Thats interesting. I’ve never heard of a BIOS on the Mac. We have OF (Open Firmware) and the old NVRAM but no BIOS.

Vasileois, I wasn’t aware of the hardware limitations. I’ve seen (and used) multi-boot systems on the Mac before, so I didn’t know there was an issue with Linux and this. I’d figure that you could simply partition the flash drive into multiple logical volumes, and have a master volume with a menu that could point the Mac OF at the chosen distro.

The issue is not with Linux, it’s with Windows, since FAT32 is a Windows file system. Macs use an entirely different one (AFS and now HPFS). I haven’t done multi boot USB flash drives on a Mac before, so I cannot give you definitive info.

Linux uses a global approach for both Macs and Windows machines. That’s why it goes with the file system boot that both of them support.

1 Like

Excellent, that clears things up, thank you.

1 Like

My pleasure, @MarkLX! :slight_smile: