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I would like to install Ubuntu to an external hard drive without touching anything on the already existing hard drive and OS installations. By doing this I am able to boot from the USB by selecting which drive to boot on startup.

I have always done this by selecting to do a custom installations on the Ubuntu installation wizard, setting the partitions myself and select the USB drive at the drop down list of where to install the boot partition.

I have run into a problem however now with a new PC and I believe it might have to do with Uefi as I have never had one before.

I tried installing Ubuntu 16.10 and even though I have selected for the boot loader to be installed on the USB drive, Ubuntu will instead move/override the existing grub partition to the USB and add both the new OS (on the USB drive) and the old one (on the internal drive) to that. This makes the internal Ubuntu installation unbootable when the USB drive is not connected since Grub is inside. I also restored the internal OS to its initial state however when I try to select which drive to boot to, the USB drive which now contains the grub with both OSes is not in the list.

Am I missing something? How can I install Ubuntu to a hard drive which I can plug and use without messing anything whatsoever in the internal disk like I used to.

ByteFlinger
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1 Answers1

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I think the easiest way is to disconnect (unplug) the internal drive from your computer. Then the installer cannot auto-select the internal drive, which is otherwise a problem in UEFI mode. So you can install 'like you have been doing before' (and this way it should work in UEFI mode too).

An other easy alternative is to start from a compressed image file, that you clone to the USB drive according to the following link,

help.ubuntu.com/community/Installation/UEFI-and-BIOS

This alternative will work also if you are not willing to disconnect the internal drive.

Community
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sudodus
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  • Really? Unfortunately this is an ultrabook meaning the internal drive is welded into the motherboard and disconnecting it may be an issue. That sounds like a huge oversight on the Ubuntu wizard software design. Did you mean that doing this in UEFI is hard and likely why it works that way? – ByteFlinger Dec 13 '16 at 22:07
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    Unfortunately, yes. I think that some manufacturers use non-standard versions of UEFI to make it hard to install any other operating system. You can try according to the UEFI-and-BIOS link. (I made that compressed image and it is portable between several computers.) I don't know if anybody has tried it in an ultrabook, but it might be worth trying. That way you can even flash the image to the USB drive in another computer. Another alternative is to make a persistent live drive. In both cases you can use mkusb. – sudodus Dec 13 '16 at 22:19
  • Thank you. The whole thing just sounds really stupid to me. I'll look into it later – ByteFlinger Dec 16 '16 at 13:27
  • You are welcome and good luck :-) – sudodus Dec 16 '16 at 13:41