CTO Articles
Published in IT World
January 03, 2006
Separating the cart from the horse
Imagine a world in which carts full of goods are designed to be pulled by a single horse. If the horse slows down, the cart moves more slowly. If the horse dies unexpectedly, the cart comes to an immediate halt and a lot of time and money is expended, pulling all the contents out of the cart for transfer to a second horse-and-cart combo.
Insane right? Now switch out the word "cart" for the word "data" and the word "horse" for the word "operating system". Data designed to be accessed by a single operating system. Data tied to a particular copy of an operating system in such a way that failures in the operating system result in time and money being expended moving the data somewhere else.
Equally insane? Yet we do it all the time. Most personal computers have a not-very-comforting way of keeping all the data on the same slab of magnetic media that is used to "bootstrap" the operating system itself. A failure to boot the operating system results in the inability to access all the user created data.
Now there are ways of alleviating this problem of course. Route 1 is perhaps the concept of an emergency backup boot disk. This is always a good idea. If you do not have one of these for your machine right now, I would suggest you stop reading and go create one. Route 2 is perhaps the concept of a backup. You do have backups don't you?
All teasing aside, the problems with route 2 are obvious. If you are lucky enough (!) for the operating system failure to happen just after you have completed a backup, you are in good shape. Set up a new machine or clean down the old one, install the operating system and install the backup. Few of us are that diligent with our backup regimes.
Route 1 is a very valuable alternative to this which, if it works, has the significant benefit of giving you access to the last saved versions of all your files.
When it comes to the risk of data loss, I believe it is sensible to err on the side of paranoia. What other routes are open to us just in case routes 1 and 2 do not function for some reason?
I use two other routes and can heartily recommend both of them. The first is to partition your disk into two different operating systems that can read each other's files. A common example of this is Microsoft Windows and Linux partitions on the same slab of magnetic media. If Windows cannot boot for whatever reason, Linux can read Windows-style file systems. Just boot into Linux and read off your valuable Windows files from there. Similarly, if Linux refused to boot you could fire up Windows and read your valuable Linux files from there with something like explore2fs[1].
The other alternative that I keep handy for emergencies, is to boot completely from CD-ROM or DVD. So-called "live CDs" are great for this. Common examples include Ubuntu Live CD[2] and Knoppix Live[3].
Even if you never use Linux on your PC, having a small partition set up so that you could boot into Linux to read off your Windows files is worth thinking about.
Keeping a Live Linux CD lying around will not do you any harm either. Putting all your bets onto a single horse (and cart) is best avoided if possible.
[1] http://uranus.it.swin.edu.au/~jn/linux/explore2fs.htm
[2] http://cdimage.ubuntulinux.org/releases/breezy/release/
[3] http://www.knopper.net/knoppix/index-en.html