I have a 64GB USB disk.

From the ubuntu official ISO images I would like to know how to create a bootable live USB that uses ext4 instead of iso-9660 fs, squashfs, and casper. Preferably with a seperate /home partiton.

Preferable I would like the USB to be bootable for both the legacy BIOS process and the EFI boot process.

As far as I know BIOS boot requires a MBR to be created and written and EFI boot requires a EFI partition.

So I imagine the final USB block device should have three partions (/home on a partion by itself)

  • EFI partition
  • ext4 partition (for /)
  • ext4 partition (for /home)

So how can I create such a live USB from the downloadable ISO images?

1 Answer 1


Full Install to USB - BIOS/UEFI

Mkusb makes a great base for a USB drive able to boot from both BIOS and UEFI, https://help.ubuntu.com/community/mkusb :

  • Use mkusb to make a Live system on the Installer USB, (2GB or larger).

  • Use mkusb to make a Persistent system on the Target USB, (8GB or larger), using default settings with up to 25GB persistence, (remaining NTFS partition is used as Windows accessible data partition).

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  • As soon as mkusb finishes, open GParted and delete sdx4, the ISO9660 partition and expand sdx5 into the recovered space, sdx being the device name of the Target drive.

  • Create a extra ext4 partition sdx6 for /home if desired.

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  • Unplug or remove HDD before proceeding further, (optional but recommended, highly recommended if it is running in UEFI mode).

  • Boot Installer drive, select Try.

  • Insert Target drive

Start Install Ubuntu...

  • Select "Something else".

  • Select sdx5, (on the target drive), and click Change.

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  • Select Use as: ext4, Format and Mount point: /.

Don't touch any other partitions (unless adding a /home partition to sdx6).

  • Select sdx5 as Device for boot loader installation.

  • Complete installation.

  • Boot the target drive and run sudo update-grub to add all drives to boot menu.

  • Copy grub.cfg from sdx5/boot/grub and paste to sdx3/boot/grub, overwriting the existing grub.cfg file.

  • Do not install any propriety drivers, (ie Nvidia), on pre-18.04 installs.

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