0

Ubuntu version: 20.04

I made a complete Ubuntu install on an old laptop HDD I turned into an external drive. I am currently able to boot it from a VM (which is also the way I was able to install Ubuntu on), but I'm lacking some capabilities I could have from using it as a host (actual) OS.

The computer I'm using isn't mine, but I still have access to the internals and could plug the disk on an unused SATA port. I also don't really need to dual boot, what would be ideal is that when my external drive is plugged I'm able to boot directly on Ubuntu and when unplugged the computer boots on the Windows 10 install of the main disk as normal.

Now my question:

Providing it would be possible, how can I boot my Ubuntu install, preferably without having to install anything on the computer main disk?

This brings the following subquestions:

  • Can I boot my install without installing a GRUB ? I heard of (U)EFI boot but I'm not sure how to proceed
  • If installing the GRUB is required, do I have to install it on the computer main disk, or can I install it on my external drive ?
  • Do I even need to bother with (not) using a bootloader and wouldn't changing disk boot order in the BIOS enough ?
CodeTalker
  • 21
  • 1
    Ensure that one of your Ubuntu disk's partitions has the "BOOT" flag set. Reboot the system, and use the BIOS to change the "Boot Order". – waltinator Oct 28 '20 at 22:09
  • 1
    Installing grub on the Ubuntu disk is necessary to get it to boot after the BIOS selects it. Read man grub-install;man -k grub2 – waltinator Oct 28 '20 at 22:13
  • If BIOS and MBR partitioning, you install grub to MBR of external drive. If UEFI you install grub ti external drive, but it goes into the ESP - efi system partition on the external drive. But a new install typically goes into ESP on internal drive. Lets see details, use ppa version with your live installer (2nd option) or any working install, not Boot-Repair ISO: Please copy & paste the pastebin link to the Boot-info summary report ( do not post report), do not run the auto fix till reviewed. https://help.ubuntu.com/community/Boot-Repair & https://sourceforge.net/p/boot-repair/home/Home/ – oldfred Oct 28 '20 at 23:28
  • @waltinator Changing boot order did the trick. Thank you! – CodeTalker Oct 31 '20 at 09:10

1 Answers1

0

Installing Ubuntu on Different drive than Windows 10

GRUB will only boot Windows and Linux if they are installed in the same Legacy/UEFI mode

  • Determine Windows 10 boot mode. Type System Information in Windows Start panel. Under "BIOS Mode" it will say if Windows is Legacy or UEFI.

  • Unplug the Windows HDD.

  • Boot a Ubuntu 20.04 Live USB in the same mode as Windows boot mode. A USB made with Rufus MBR partition scheme option will boot either way. If Windows is UEFI use Rufus GPT scheme, See Unable to access Ubuntu from UEFI

  • If the HDD is empty, at "Installation type" select "Erase disk and install Ubuntu", then complete the installation as directed. For encrypted drive that will boot BIOS or UEFI see: Installing Ubuntu on a LUKS encrypted USB thumb drive

  • If there is data on the disk you wish to preserve, Install Ubuntu using the "Something else" option.

  • if asked by Something else, create a 500MB EFI system partition on the Ubuntu HDD.

  • In Something else, Select the Ubuntu HDD for bootloader installation.

  • Continue installation as directed.

  • When complete, Plug in the Windows HDD. Set the New Ubuntu HDD as first hard drive, run sudo update-grub to ensure all bootable drives are on the boot menu.

  • With drive plugged in you have a choice to boot Ubuntu or Windows if drive is unplugged Windows will boot as normal.

C.S.Cameron
  • 19,519