I have an unassigned HDD that has 3 partitions, which I would like to keep separate.

I don't think the Unassigned Devices plugin supports formatting drives with multiple partitions (only allows to delete all and replace with a single partition).

 

Does anyone know how to do it with the console?

Edited September 10, 20187 yr by testdasi

You might want to google for the linux ‘mkfs’ command that is used to format disks under linux.   Note that when doing it this way you need to specify the partition number as part of the device name (I.e.  use a name of the form /dev/sdXN) where N is the partion number on the device.