How to run Linux from a USB drive

Nothing can beat having a great Linux distro installed on a super-fast hard drive, with all your favourite apps configured just how you like them and all your files at your fingertips.

But this has one major drawback: perfect as your setup is, it's also just one machine, and sooner or later you'll be forced to leave that computer behind and use something else.

Something that might run Windows. Something that might not even have Firefox. Because no one likes being parted from their data for too long, we present a smarter option: store it all on a USB flash drive.

In older days, you were able to store Linux on a CD and use a flash drive just to save changes. After some advancements, you were able to run Linux straight from the flash drive, but it didn't store any changes you made. But the latest generation of Linux distros – namely Ubuntu 8.10 and Fedora 9 – have a memory overlay system that allows you to store your Linux distro and any changes you make to it on a single flash drive. Sure, you'll need at least 1GB to be able to fit the entire distro on there, but it does mean everything you need is all on the one device.

Once you switch your install to a flash drive, it means you can take it pretty much anywhere and get back to work immediately. Whether you're using a server, a desktop or even a tiny little Aspire One or Eee PC, the vast majority of modern computers support booting straight from USB, so you can just plug in your drive and go.

You'll need a flash drive with at least 1GB of free space, and ISO images of either Ubuntu 8.10 or Fedora 9. It's likely there are other distros out there that work with similar or perhaps even identical instructions, but Ubuntu and Fedora are the big two so we stuck with them.

Before you begin - Don't just abandon your hard drive-based Linux distribution – decide on these important questions first.

One of the first thing you encounter when switching to free software are people who want to let you know all about the difference between free beer and free speech, and that's all very nice. But for most us, nearly all our software is free of cost and free to modify, so in our minds we balk at the idea of paying for functionality. However, if you want to put Linux on a flash drive you really do have to fork out and buy some hardware, so if you don't already have a good flash drive you need to read this first.

There are five things you'll want to consider when buying the perfect flash drive for Linux. If we order them with the most important first, it looks like this:

1. Reliability

This is easily the most important thing to care about, because it doesn't matter how cheap, fast and spacious a flash drive is when it dies after 20 minutes. If losing your data is simply not an option (and, let's face it, that's almost certainly the case), go for a brand name you trust – we chose Corsair, because it's a company with a huge amount of experience making quality flash drives, and its Flash Voyager range is designed to be water- and shock-proof.

2. Cost

This is always going to be a consideration, but fortunately flash prices have dropped dramatically in recent years – whereas 256MB drives used to be £60 or £70, you can now get 32GB drives for the same price. That's over 100 times the capacity for the same price!

3. Capacity

1GB is the absolute minimum needed to get started, but it really depends on how much data you want to store – and also how much extra software you want to install. If cost is an issue, the best value drive sizes right now are 4GB or 8GB.