Installing ubuntu on external hard disk

[Alan Pope]

On Thu, Mar 08, 2007 at 01:01:11PM -0800, Jared Buck wrote:
> Hi all,
> 
> I'm wanting to install ubuntu on an external hard drive (which is designated
> /dev/sda by the system), and partition it into two parts, an ext3 system and
> a swap partition, the ext3 system is labled sda1.  Now, the installation
> appeared to go well.  But when I try to boot into the ubuntu system on the
> external drive, it gives me an error message:
> 
> ALERT! /dev/sda1 does not exist.  Dropping to a shell!
> 

Take a look at this guide on the wiki:-

https://help.ubuntu.com/community/BootFromUSB

Especially the sections on grub.

Cheers,
Al.