In case you need to experiment with different OS from one that you already have installed, but don’t want to take a dual-boot approach to avoid possible corruption of your main disk, then keep reading this article – Installing Ubuntu on an external bootable HDD.


Although it is possible to run Linux along with Windows on the same hardware (dual-boot approach), I’m not an advocate of such approach as there are many possible combinations and possible complications, while no clear benefits can be observed.


For example, one may have Windows installed first, and then some variants of Linux, while in other case you might have some Linux flavor installed first and then you want to install Windows.


You may have even several Linux distros + Windows which is called multi-boot.


Then there is BIOS and UEFI component to deal with.


Additionally, many modern Linux distros like Fedora by default are using Volume Manager + file encryption of your Home directory, thus besides classical disk partitioning you may end up dealing with Volume Groups and many sub-options.


To keep everything simple and avoid mentioned complications as a result of many options available, installing OS on the external disk is a way to go.


In this example I want to create bootable and writible Ubuntu 18.04 LTS external HDD.


Here are the steps you need to execute:


1. First you need to create Ubuntu bootable USB stick.

One of the easiest ways of how to do that is to execute the following command (prerequisite is to have ddrescue package installed):

ddrescue ubuntu-18.04.2-desktop-amd64.iso /dev/sdb --force -D


2. Boot your machine by using created USB live Ubuntu bootable stick.


3. Follow the guide from this link:


The only change I made from mentioned article is point 11, where I have to allocate smaller amount of space for a primary partition (about 50 GB), as in case if I allocate larger amount (e.g. 500 GB), HDD did not want to boot.



Creating external writable bootable disk with different OS that you want to experiment with is definitely a way to go, as it’s more safe and easier to use than dual or multi-boot approach.

In case you have a fast SSD disk and faster interface (like USB 3.1), this option might also boot fast enough, so you won’t notice a significant difference in speed when comparing with a boot from your main drive.

Although there are many links on the Web related to creating external disk, difference is that I want external disk to be:

  • bootable (like a standard Linux live disk)
  • writable (standard Linux live USB is read-only)
  • without all complexity, complications and risks to corrupt main disk which might happen if you take a dual and multi-boot approach

Windows users might run Linux within Windows, but I haven’t tested if that option can cover all cases (especially if you want to experiment with nVidia CUDA application development toolkit).


In my case, motivation to install a second operating system was to be able to experiment with CUDA development for which I needed to install Ubuntu (VirtualBox doesn’t work with CUDA as per virtualization restriction, while Fedora, my main operating system, releases a new major update every 6 months, while nVidia CUDA Development Toolkit release cycle is a way slower).


Whatever motivation you might have, hopefully this article will help you to easily and safely experiment with various operating systems and to remove existing barriers imposed when running only one.

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