My goal: try to install Ubuntu on a separate partition of my laptop's HDD which would only be bootable with an inserted USB drive. This drive would contain GRUB and additional ext4 storage, without it the laptop will boot into w8.1 regularly.
My problem: constant installation failure. I've maxed the available space to 20gb on HDD, 16gb on USB. I reckon it could be that my HDD is bitlocker encrypted but I have yet to decrypt it and try again. I am booting with UEFI hybrid with CSM.
I'd like to know whether there's a problem with my concept or if there are some crucial technical details I'm missing.