The statistics make scary reading: 31% of PC users have lost all their files due to events beyond their control - floods, a lightening strike, theft, viruses. And yet, it's estimated that fewer than 10% of PC users regularly back up their work. If you work in a corporate blue chip your IT department will probably take care of backing up, but for SMEs it's a big issue - and one you should take very seriously.

There are two types of things you may need to keep: programs and data. Unless your work involves creating software tools, programs are easily replaced. You can keep the backup CDs off site, buy replacement programs off the shelf or download them from the internet. The truly critical files are the ones you've created, in other words, your data files: documents, spreadsheets, accounts, etc. Such information is the lifeblood of your business and desperately difficult to replace if it gets lost.

How often should you back up?

The short answer is "regularly and frequently". Exactly how often you need to take backups varies according to what you're working on and even the sort of machine you're using. Desktop PCs are moved very seldom, but it's estimated that one laptop is stolen or lost every 43 seconds. Mobile devices which are used off site accumulate ad-hoc information and are much more vulnerable to damage and theft. They should therefore be backed up more frequently.

As a rough guide, work out how much data you can afford to lose in terms of the time you spent creating it, and then back up more often than that as part of your routine. Backups exist to make life easier, so there's no point in backing up data you can afford to lose. If it's vital the information is kept then calculate how long it would take you to reinstate it the hard way - by re-doing it from scratch - and work out how much time it takes to back up the data, and then decide accordingly how often you need to do it.

And don't forget to test the backups from time to time by reinstalling them. Some 34% of companies fail to test their backups and of those that do 77% have found backup failures.

Of course it's boring and a waste of time to sit and watch a machine while it chugs through backing everything up, so make sure that your backup procedure is automated. The usual procedure is to do a full backup periodically, perhaps weekly, and an incremental backup of new or modified files according to how much data you have created.

Data storage options

There are four main media available for storing data and thus for use when backing up: writeable CDs and DVDs, magnetic tape, removable hard drives and online data transfer to a remote site.

CDs and DVDs are fine for short-term backups but can get confused, lost or damaged unless properly labelled and filed somewhere safe. Separate tape drives are extremely reliable and can store huge amounts of data. Removable or external hard drives used to be the preserve of technical specialists but they've become both cheaper and easier to use. There are several extremely fast and reliable types available, depending on what you want to do. Zip drives, for example, hold a huge amount of data while some portable hard drives can store the entire data from a PC and still fit into a pocket. Mini USB drives are even smaller - the size of a car key - but can still store as much as 2GB of data (enough memory to store 65,000 letters!) and are ideal for backing up a laptop while off site.

Whatever system you use, you should take at least two backups, one for keeping in the office and one for storage off site. Office storage must be lockable, waterproof and fire-proof, too, for obvious reasons! For a monthly fee, specialist firms offer online data storage services, where your backups are done automatically for you via the internet. Arrangements differ according to the service used, but file retrieval is easy and many firms also offer to reinstate lost data from the back ups they hold, if necessary.

It's good practice to take a cyclical series of backups so that you have an extra buffer in case one backup has become corrupted, for example by a virus. The system is sometimes called "grandfather, father and son" and works by overwriting grandfather to create grandson. Companies offering online backups will discuss with you what you want backed up, how many versions you want to keep, and how often backups should be taken.

Starting from scratch

To decide what back ups you'll need, imagine that a fire has destroyed your office (stop smiling at the back there!). When you re-equip you will almost certainly upgrade at the same time. If your backups are to be useful your new machine needs to be able to read them. It's therefore a good idea to store backup data as simply as possible - ie not compressed or password protected - and create them on the most up-to-date equipment you can.

Backing up may be tedious but it's vitally important. Business information has an intrinsic value. It's estimated that 60% of companies which lose their data go out of business within six months of the event. If the worst happens, you need to be able to get back to work as quickly as possible. To do this your data must be safe and available whatever other disasters have occurred.