PUBLISHED : Sunday, 20 May, 2007, 12:00am
UPDATED : Sunday, 20 May, 2007, 12:00am

Many years ago, when I started using personal computers, I had no idea what I was doing. I did get advice from a boffin and he helped me a great deal. He used to talk about the need to backup data.

I learned my lesson the hard way but I'm confused about how it all works with current technology. In the old days, I started backing up on floppy disks then Zip drives then some other thing I have long since forgotten. I have a new computer, which has 100 gigabytes of space! How am I supposed to back that up? Also, my family is 'mixed': some of us use Macs and some use PCs. There are quite a few operating system versions in that bunch, too. It's a mess. Can you help?

Tom, New Territories

DQ: Most of us have experienced it: a feeling of dread in the pit of your stomach the moment you realise your data has been lost. It is not fun and for some, it can be extremely expensive. First of all, check out your machine then divide all your data into three categories: 'can't live without', 'really important' and 'nice to have'. Whatever falls in the first category must be backed up to an external hard drive on a regular basis. Ideally, if it is not too big, you could even burn that data to several DVDs. If you have a great deal of data you cannot live without, you will need a second or even a third external hard drive. Drives are cheap but they also break down. I would make three copies of everything just to be safe. For the second category, a single backup should be sufficient. For the last group, you could either treat it like the second category or leave it on your computer's hard drive. If it's lost, you won't be too bothered.

There are several other issues to consider. Most operating systems come with some form of reserve function, which supports incremental backups. If you have a 100-gigabyte hard drive used for backup purposes, the initial saving process could be time-consuming. However, every incremental backup thereafter only backs up recent changes, which is much faster. This should extend the life of your external hard drive; you can even set a timer to perform the task in the middle of the night.

You may also want to check out commercial software designed specifically for backing up because the interface may be a lot easier to use.

For those who have not experienced significant data loss, you are uncommonly lucky. It will happen some day and Sod's Law says it will happen at a time when it will do the most damage. There is no excuse for not backing up data. The loss of all your files rarely goes down well with friends, family or colleagues. When was the last time your dog really did eat your homework?