I am installing Ubuntu Server on an old Mainboard. The Mainboard is not supported anymore and has problems booting from GPT media.

I'd like to use the whole disk for the Ubuntu installation. Is there an option to use the setup assistant and create a MBR media instead of a GPT one? I can't find it and I did not find something reasonable when googling the problem.

  • Is the computer UEFI... or only an old BIOS machine? How big is the HDD? What problems did you have booting from a GPT HDD? You can use gparted to first create a MBR partition table, then go back and install Ubuntu Server. – heynnema Jan 13 '20 at 16:20
  • It is an old BIOS machine, the HDD is a 240 GB SSD and when trying to boot, the message "no bootable device found" comes up. – user2154065 Jan 13 '20 at 16:25
  • What brand SSD? Did you, or can you, use gparted to install a fresh MBR partition table on the SSD (this will wipe the drive), and then install Ubuntu Server? Some old BIOS machines can't boot if the boot files required are too far away from the front of the disk. – heynnema Jan 13 '20 at 16:54
  • I created a blank MBR drive on the SSD (WD/Western Digital) and reinstalled Ubuntu, but Ubuntu switched the drive back to GPT. I could solve the problem by adding the active flag in the protective MBR, as described in my answer. Thanks for your help! – user2154065 Jan 13 '20 at 23:05

I solved the problem simply by setting the boot/active flag in the protective MBR. I expected the Ubuntu setup to do this by default.

To set the flag, I used fdisk. The command fdisk -l lists all the available devices, to identify the correct path (e.g. /dev/sda).

The command fdisk /dev/sda starts fdisk for editing the disk content. To add the boot/active flag, enter the following keys and then press return each time.

M    # Start Editing the Protective MBR
a    # Toggle Boot/Active Flag
w    # Write Changes
q    # Exit fdisk

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