How to backup your computer.
With the low cost of CD and DVD writers and media, there is no longer any excuse why you cannot make a regular backup of your computer at home or in your small business. A good CD or DVD mastering program will not only make it easy to backup your critical data, it will also verify that all the data has been correctly copied on your backup media. However, if your business is larger and runs more complex software you may need a real backup program that can copy files that the application still has open.
A good backup strategy starts by deciding what needs to be backed up and how often. If you have a good overview of your information assets from your risk analysis, you will be sure that you won't forget anything crucial like your email address book or your latest additions to your image archive. Frequency of backup can vary from monthly to hourly. Frequent full backups also protect you against the, in general, more unreliable CD and DVD media compared to professional backup tapes.
If you make a full backup weekly, you can use an USB stick to backup the (word processing) files you have just been working on. You don't want to lose several hours of work when your system crashes. You can also use a multi-session CD for incidental backup. Just make sure you save multiple versions of your files, never overwrite a backed up file.
While you can backup your system as well as your data, I prefer to keep a good log of what I installed on the system and make a fresh install if the system fails. Properly separating system files from data storage when you setup your system will make it both easy to backup all your data, as well as to regularly install a fresh system. You'll be surprised how well your system runs after a yearly (or half yearly) fresh install.
For home users or small business it often is easiest to make a full daily backup of your critical data. That way it is not too difficult to track where you can find the file you just deleted by accident. Store your backups away from your computer and make sure you do a risk analysis for these assets as well. If the data on your backup is confidential you will need to protect it as such. Put it in a safe and safely destroy any backups that you don't need anymore.
Common practice is to regularly take backups off-site to ensure availability after fire of theft. Again you'll have to decide how often. You might want to consider taking copies of your documentation off-site as well.
Finally, a backup plan is inefficient unless you test it. Testing your backups should be done regularly, not only to make sure all your files are still readable, but also to see if you did backup all your data. So, when you buy a new hard disk for your system (or a new system), you'll have a great opportunity to find out if your backup plan is really working by running the new system from your recent backup. This time, at least, the missing files will still be on your old hard disk.