The problem: I want to install Ubuntu on my HDD, but after the installation process from the Installation-USB, the HDD won't boot up and does not get shown as possible boot device.

I have a 5TB WD Elements HDD. I have yet no storage on it so I can totally mess around at that HDD. Since I want to use 4,8TB of my HDD for pure storage (exFAT) and only 200GB for Ubuntu, I pre-partioned the HDD that way.

In the Ubuntu installation progress, running from a live-USB-Stick, I choosed "something else" as an option, formatted the 200GB to ext4, primary, / as root and below my external HDD as device for the bootloader. Finished the installation, rebooted and no device was found.

I also tried other stuff:

Preformatting in gparted



Creating an additional swap-partition of something like 10GB (always used different sizes from 5-10GB)



Creating an additional bios-partition



Using the 200GB partition for the bootloader instead of the whole drive



Using the whole drive as an installation medium (not preformatting it myself)



Trying to boot up the HDD on different computers

There probably seems to be a problem that the boot partition is not working or something like that. The system partition seems to exist and the installation progress was always finished successfully (until the reboot)

I successfully did several installations of Ubuntu before on internal HDDs. So I am wondering why this is not working on my portable HDD. Neverless what I do, neverless what tutorial or forum post I read, I did not get it to work. I did at least 10 full installations. I just want a portable HDD that can boot up while beeing connected at any PC.

Can anyone help?