Better safe than sorry! How to achieve reliable backups of vital data.

The importance of backups

by Veronica Yuill

If you rely on your computer to run your business (and who doesn't these days?), it is essential to have a planned backup strategy to prevent loss of vital information in the event of fire, flood, hardware failure, theft -- or simple user error! This article is written from the point of view of a PC user, but the general principles I have described can be applied to any type of computer.

Step 1 - Organise your data

Basically, there are two types of information on your computer: data files (your work) and application (program) files, such as Word, Excel etc. First, make backing up easier for yourself by separating your work from program files. If you are fortunate enough to have more than one hard disk drive, you could store your application files on one drive, and your data on another. Otherwise, simply create a directory off your root directory, called for example c:\work. Then store your data in subdirectories of this, for example one subdirectory per project. Now, you can back up your work by simply selecting the work directory. All its subdirectories will automatically be included, so you don't have to remember to update your backup when you create a new subdirectory. Program files, which don't change frequently, can be backed up separately, at less frequent intervals.

Remember, though, that this practice isn't feasible for some programs, e.g. email clients, which store their data in their own directories. If you're reading this, your email is most likely vital to your work, so don't forget to include this directory in your regular backups!

Step 2 - Plan your backup strategy

First, look at the volume of data you need to backup. This will help you decide on the appropriate media to use for your backups. If you have organised your disk as suggested above, you can simply right-click on the "work" directory in Explorer, and then click "Properties" in the popup menu. This will total up the size of all the included subdirectories. Also try to estimate how much the volume will have grown in, say, a year's time, and take this into account when selecting your system.

Once upon a time it was feasible to backup onto ordinary floppy disks ... but as the available disk space increases so does the volume of files we find to put on it! Depending on the volume of information you have you are probably looking at either a) zip disks, which will take up to 250Mb, or b) tape cartridges, which are measured in gigabytes, but are considerably more expensive. A third possibility is rewritable CD-ROMs -- the cost of CD drives capable of writing disks has come down a lot over the last couple of years, as has the cost of blank CDs.

Remember that most backup software will compress your data, so the capacity of any given medium can be multiplied by 1.5 to 2, i.e. you could expect a 250Mb zip disk to hold about 400Mb of files. Ideally, you should select a system with the capacity to do a backup of all your data unattended (i.e. you don't have to be there to change disks/tapes). This suggestion is based on the principle that if it's a nuisance, it won't get done!

Now, think about how often your data changes (or, looking at it another way, how many days/hours of work you are prepared to lose in the event of total system failure!). This will help you decide on the frequency of your backups. For most people, a daily incremental backup (i.e. just those files which have changed since the last backup) plus a weekly full backup will be ample.

Also think about how long you need to keep backups before re-using the tape or disk. If you have unchanging data that needs to be kept long-term (e.g. a finished project) you should consider archiving it onto zip disk or CD-ROM rather than continually backing it up with current work.

Step 3 - Make it easy

Having decided on what to back up, and how often, and selected what medium you are going to use, buy enough blank disks/tapes to set up a rotation. You should have at least two sets for each type of backup, using them alternately. This way, you have a fallback if the most recent backup turns out to be unusable. I have two tapes for incremental backups, one of which is used on Monday and Wednesday, and the other on Tuesday and Thursday.

A further three tapes are used in rotation for Friday's full backup (this may seem over-cautious to some, but two total hard disk failures within a month of each other made me this way!). Incremental backups, being small, are appended onto the tape till it's full, so in practice I have several months' worth available should I need them. Whatever you do, never backup over your only existing backup!

You'll also need to plan an occasional full system backup (programs plus data). This can be done less often, since programs rarely change (unless you are like me and are constantly installing new and exciting software!).

Now, set up your software to make life as easy as possible for yourself! Cartridge tape drives often come bundled with backup software which allows you to set up named "backup sets". So you can easily create sets for your incremental and full backups. Backing up your data is then simply a matter of selecting the relevant set and clicking "Start". Microsoft Backup, which comes as part of Windows, lets you do this as well. The software that came with my tape drive goes one better; it has a "Schedule" option which means that I can set it to run jobs at particular times. So all I have to do to ensure my work is backed up each day is to select the right tape and put it in the drive -- the software does the rest for me while I'm elsewhere!

And finally...

Now that you have a nice warm feeling looking at that stack of zip disks holding your precious data, just a few final words of caution:

• don't store your backups next to the computer!

Fire, flood, or other calamities could wipe the lot out. At least store backups in a separate room (and preferably keep one set offsite). By the way, a car is not a particularly good place to store backups since magnetic media are sensitive to variations in temperature so a couple of hours parked in the sun or in sub-zero temperatures could render them useless.

• test your backups from time to time; in other words, try restoring files from them to a temporary directory on your PC, just to check that the disk or tape is readable.

If you get yourself organised, backups really don't require a lot of time and effort on your part. Don't wait for disaster to strike before you take action -- do it now, and enjoy the satisfaction the first time you calmly recover a precious "lost" file from a backup!

© Archetype IT Ltd, 2000

Veronica Yuill is Development Manager for Archetype IT, a web development company with offices in France and the UK. She lives in rural France and works on web sites and other Internet-related projects for clients around the world. With fifteen years' experience of systems analysis and programming, Veronica specialises in creating dynamic, database-driven websites. She also teaches on a ground-breaking online degree course offered by the UK-based Open University. When not gazing at a computer screen, she spends her time enjoying the Mediterranean way of life. Her ambition is to continue to learn something new every day.