Hard drives fail, CDs become unreadable, viruses infect computers and destroy files, computer users accidentally delete files and folders and format drives. But there is no excuse for losing precious files. The way to protect your files is very simple. Have a backup. Keep a copy of your work somewhere else, in a safe place - or preferably two copies, because a backup can fail.

All modern computers have CD writers, or even DVD writers, so they already provide a place to back up your files. External USB hard drives and high capacity Flash memory drives are inexpensive, and have the advantage of being faster and instantly writeable. Windows XP doesn't include backup software - the NT Backup found in some distributions is unsupported and doesn't support optical drives - but backup software is not expensive. It's certainly cheaper than most data recovery software, and that's without taking into account the cost of data loss in time, nerves and temper.

Don't trust your valuable files to something that is going to fail some day. Don't wait for disaster to teach you that you should have had backups of your data. Get some backup software now and start protecting your files today!

Conventional backup software

Most backup software is the kind of backup software that you will typically run at the end of the day. It will make a backup copy of your files, as they are at that moment in time, and burn it to a CD or DVD, or save it as a backup archive to another drive.

Conventional backup software can perform most if not all of the following types of backup:

• Full backup - a complete copy of everything on the computer, or everything in the folders you choose to back up. This is good, but can take a long time.
• Incremental backup - a copy of everything that has changed since the last full or incremental backup. This can be fast, and is used to update a full backup, but if you need to restore it can take a long time, as you need to restore the full backup plus all the subsequent incremental backups.
• Differential backup - a copy of everything that has changed since the last full backup. This is used to update a full backup. It takes longer than an incremental backup, but is more convenient to restore because the last full backup plus the last differential backup are all that are needed to restore all the latest files.
• Mirror backup - this is like a full backup, but instead of storing the backup copies in a compressed backup archive, it creates an exact copy of the original files and folders. This is useful when space for storing the backup copy is not at a premium, and you would like the convenience of being able to access the copies without using restore software to extract them from the archive.

Except in the case of a mirror backup, backup software stores copies of files inside a backup archive, compressed to save space. Some backup software uses a proprietary format to store the data, but many store the data using the industry standard Zip format. This means that you can access the backup copies to restore selected folders or files using any Zip file management software, including the compressed folder support built into Windows.

Continuous backup software

This is not the only way to back up data. Continuous backup software makes a copy of a file whenever it changes. Called continuous backup, instant backup or continuous data protection, it is not suitable for every situation because it can use a lot of storage space and processor time. Continuous backup also requires an always-available second disk drive to write the backups to in real time - it isn't suitable for use with CD or DVD writers.

But continuous backup is an excellent companion to conventional backup software as it protects against loss of work done since your last backup. It can also provide you with a version control system, as it lets you restore any previous saved version of a file, not just the latest. Some continuous backup products even include tools that allow you to compare the differences between versions of a file.

Continuous backup - it is an install and forget solution that gets on with its job in the background. But when you need to restore something, even if it's something you deleted or overwrote a few minutes ago - which a conventional backup would not have backed up - you know that you can get it back.

Near-continuous backup software

If you don't need instant, continuous backup then you can have a half way house: a backup that runs regularly throughout the day and copies all the files that have changed since the last time.

Some conventional backup software including AllSync can do this by scheduling an incremental backup to run at intervals. Though primarily a synchronization tool, AllSync also has powerful backup capabilities and can run in the background, backing up your files while you work.

Which backup method to choose?

Which backup method is best for you will depend on how you use your computer. If you work office hours then it's easy to remember to back up at the end of the day, especially if you use a program like AllSync that can create a desktop shortcut which will run a backup and then shut down the computer. Just click the backup icon and walk away. If you're a home user and use the computer at irregular times then it's harder to get into the backup habit, but it is still a good habit to get into.

If you're constantly editing files - Word or Excel documents, web pages, graphic images or program code - then continuous backup is essential. It's essential not just for the protection it gives against loss of work since the last backup, but also for protection against undesired changes, when you make a mistake and want to get back a version of the file that you had before.

For what it's worth, we use AllSync for occasional full system backups and daily full backups of all our work folders, plus AllSync to provide continuous backup and version control of our work folders.