Few people need to be convinced of how important it is to back up their data. However, the way that data is backed up -- and how reliable the backup is -- is just as vital. Imagine trying to restore the one backup copy you have of that irreplaceable Word document or spreadsheet only to find the disk you burned it to can't be read anymore.

In my case, I don't have to imagine that particular scenario: it happened to me. I lost over 5 GB of images that I had stored on a hard drive, and my one DVD-R backup couldn't be read at all. Thankfully the missing data was also backed up to another computer -- in itself an argument for the usefulness of remote backup.

		Five Backup Services
		•  Introduction •  AT&T Online Vault •  Carbonite •  eSureIT •  iBackup •  Mozy •  Conclusions

Remote backup services have been gaining ground for individual and small-business users in the last few years, thanks to the proliferation of broadband connectivity and cheap server-side storage. Also, people are a little more comfortable now than they might have been a few years ago with trusting their data to an online service, especially if the data's encrypted on the user's computer and not readable by the provider.

For this roundup, I looked at five popular online backup services -- AT&T Online Vault, Carbonite, eSureIT, iBackup , and Mozy -- with plans that start at free and scale up to professional-level tiers costing hundreds of dollars a month. I put together a sample batch of backup data -- about 200MB of documents and images -- and performed both backup and restore operations on this data with each service.

Surprises abounded: The biggest name in the lineup -- AT&T -- had the single least impressive product, and the one service with a free offering was among the best. I was also pleased to learn that at least one of the backup plans (Carbonite) allows theoretically unlimited storage. This doesn't mean you can actually store terabytes of data (you can only upload so fast, after all), but it does mean you won't run into any sudden and inconvenient capacity limits.