Lab

Online Backup

Areliable computer is a great asset, but at some point all but the luckiest of us has probably experienced some kind of hardware failure. If your hard disk gives up the ghost you could be waving goodbye to irreplaceable documents. In recent years our PCs have taken custody of our record collections, photo albums and home videos, which means they contain gigabytes of memories that could be lost forever.

Of course, that needn't be the case. Storage is cheap, and a good backup program (see the box below) will let you regularly copy crucial files to a spare internal, external or network drive. If the worst happens, though, your memories could still go up in smoke.

Home internet access has sped up a lot in the past few years, however, and for most of us it's now realistic to back up significant amounts of data online. A rash of companies promise fast, secure online backups, but what should you look for when choosing a service?

Encryption factor

If you're about to upload your most important documents to a backup service, chances are they'll contain plenty of data that you want to keep private. It's essential that the software you choose encrypts your data and transmits it to a data centre using a secure protocol such as SSL, and that the data centre itself is properly managed and protected.

A good online backup service should understand that the privacy of your data is paramount, and the best are proud of the systems they use. Check the security details on the website, and if in doubt call the company and ask them to talk you through their arrangements.

All the services tested here encrypt data using a key that is known only to you, although some, such as Carbonite, can securely store a copy if you permit it. Forgetting or losing your key will otherwise render your backup completely useless, so it's very important that you don't.

Bandwidth wagon

Encrypting data increases its size, so online backup services need to be able to store many gigabytes of data. Some clever features help them minimise the impact on your broadband connection, but you should still check whether your backups will take you over your ISP's bandwidth cap or fair use policy.

Using compression makes typical uploads and downloads smaller than the source files, while a technique called in-file delta allows the software to spot small changes in large files, and copy only changed portions to the server. We tested this feature by modifying a Wav file and a TIFF image before carrying out our second backup. Services which only back up only the changed portions would reduce the second backup size by around two-thirds.

If you have multiple computers, look for services that don't restrict you to backups from only one PC. You'll find this information in the table on page 124.

In this labs test we've examined the entry-level package from 10 different services, testing how well they cope with everyday backups. Three with the least storage space are free, although their providers clearly hope that you'll want to upgrade at some point. Each company offers additional space and features if you don't mind paying a few pounds more, but in some cases you're better off saving your money. Read on to separate the lifesavers from the timewasters.