Installing Ubuntu on external hard disk

Installing Ubuntu to the external hard drive is the same process as installing it to an internal hard drive. The same care must be taken, in that you need to ensure you have selected the correct drive partitions to install Ubuntu to. If you have not already done so, I would strongly recommend using the Windows 7 partitioning tools to resize the existing partition on the external drive to make space for Ubuntu. You can do this using the LiveCD, but NTFS support is not 100% foolproof in Linux so you may suffer data loss if you do it this way.

As for Grub, you really should install that to the external hard drive as well. When the computer boots, Grub will look for its files on the external hard drive. Without these files the system cannot boot. If you leave the external hard drive connected every time you boot then that won't be a problem. But having Grub on your external hard drive is preferred. Just ensure that your computer looks to boot from USB before any internal hard drives. Then, when you have your external drive connected Grub will be loaded first and will actually have a menu entry for Windows 7 if you want to boot from that. In addition, you can use the Ubuntu on this hard drive when connected to any computer which boots from USB first.

For running Ubuntu/Linux off an external hard drive connected via USB the process is actually quite simple to do. Here are the steps, or rather, the steps I took.

Please Note: The following steps were tested using Ubuntu Version 9.10, but has not been tested with the later versions. Use at your own risk & discretion.

What You Will Need

1. A Computer with Internet access.
2. A LiveCD or LiveUSB with Ubuntu.
3. An external Hard Drive with USB capability.

What To Do

1. Open up your computer and remove the Hard Drive.
2. Plug in your external USB Hard Drive via the USB cable.
3. Stick in your LiveUSB or LiveCD and then boot up your PC.
4. Open up the boot menu, and choose to boot from the LiveCD/LiveUSB.
5. During the installation process you should your external hard drive listed, install Ubuntu to that.
6. Finish the installation process, turn off your PC, and put your other hard drive back into your computer.
7. Reboot your computer, go to the boot menu and select your external hard drive and attempt to boot from it. If it does congratulations, you now have an external hard drive with a full fledged Operating System on it.
8. Enjoy your external hard drive running Ubuntu/Linux! Please do let me know if this helps you! If not let me know about that too. :)

We have an excellent guide & video on installing ubuntu to an external hard drive or usb device.
I have copied & pasted the main details below.
Have a look at this link to my personal website for more details & a video.

**

How To Install Ubuntu To A Usb Drive

We recommend using a live CD/DVD and unplugging any other USB drives as this makes life easier. We will assume that you are using an unpartitioned Usb drive and CD/DVD for this guide.

Insert the Ubuntu live CD/DVD, switch on the computer, and tell it to boot from CD/DVD using your 'Bios'.

It will take a couple of minutes to load and you will be presented with two choices. 'Try Ubuntu' or 'Install Ubuntu', you should select 'Install Ubuntu'

You will then be presented with a number of options.

You need to select the bottom option 'Something Else'

This will bring you to the partitioning menu.

Your Primary hard drive will be listed as 'Sda' followed by any partitions that are on it like Sda1 or Sda2.

Below this will be your usb drive, it will be listed as 'Sdb'.

Click on 'Sdb1' which is the only partition on the drive and select 'change'.

You need to select 'use this partition as Ext4 File System'

(some distributions such as Mint reqiure you to manually select 'format' at this point)

Then you need to set the 'mount point' as '/' which is the root file system and click ok. You will be taken back to the previous menu and that partition will have a tick next to it.

Now click on 'Sdb' just above that partition, this selects it as the device to install to.

Now just below is an option for where the bootloader is to be installed.

It is VERY IMPORTANT that you CHANGE THIS OPTION.

THE BOOTLOADER MUST BE INSTALLED TO YOUR DEVICE listed as '/dev/Sdb'

If you do not do this the bootloader will be installed to your internal drive.

You are now ready to install to your external device, simply click 'Install'

You will need to answer a few simple questions like 'name' and 'create password', then you can sit back and relax.

Additional Information

You will need to tell your bios to boot from the Usb device each time you want to use it.

You can easily set USB as your first boot device in the bios, and your normal system will load if the device is not connected.

Do not be surprised if your Usb installation takes 3 or 4 minutes to fully boot, especially when using a cheap Usb memory stick.

If you choose to install from a usb drive instead of CD/DVD, or you have multiple hard drives and Usb drives connected you need to make sure you are installing to the correct device, as it may not be sdb.

The easiest way to ensure that you are installing to the correct device is to use disk utility.

Open disk utility before connecting the device and note the devices on the left.

Then connect your device and it should appear at the bottom of the list.

Click on that device and look at the top right of the window for 'Device'.

It will say something like 'Device : dev/sdc' and so 'sdc' would be the device you need to install to.**

You just have to select the right device during the installation of Ubuntu. An external Hard Disk Drive works like a 'normal' internal HDD.