Keeping your data backed up is second nature to many Mac users simply because of Time Machine. Those who never made a copy of their digital data now have a reliable and invisible fallback.

Of course, a belt-and-braces approach of Time Machine and another external drive copy is the recommended regime. That might sound over the top, but losing every byte of data is much more painful than keeping track of two backups.

A double backup is a good idea, but does suffer from one fatal flaw: both copies are, generally, in one place. Unless you back up at the end of every day and take your backup 'off-site', all your data is still at risk. Fire, flood or – less catastrophic but still data-destroying – electrical surges and wayward cups of tea are all capable of destroying a hard drive.

So what is the solution to this issue? Storing your backups online, obviously.

Until recently though, remote data storage was the preserve of big businesses. However, you can now feasibly have a home backup procedure that includes a totally secure off-site element. With an off-site backup, no matter what the disaster you can recover your data. Fire, flood, swarm of locusts – never again will your data be at risk.

We've put six of the best online backup tools to the test.

Tools on test

1. Backblaze - $5 per month (£3.20)
2. Carbonite - £41.95 per year
3. CrashPlan+ - $5 per month (£3.18)
4. iDrive Pro - $4.95 a month (£3.17)
5. Livedrive - £3.95 a month
6. Mozy - £4.99 a month

Test one - Value for money

group 1

Naturally, your data is priceless and no amount of money is too much to protect it. In the real world, however, just about everything has a price. None of the services could be described as prohibitively expensive though.

Here the clear loser is iDrive, with its $5 (£3.16) a month charge limited to just 100GB of data. It does offer 2GB for free, which is fine for smaller storage needs, but not for a full backup.

Backblaze, Carbonite, CrashPlan and Mozy offer unlimited storage for your monthly fees. You can pay for a number of years up-front to reduce costs further. However, CrashPlan gets extra points for offering a family pack solution that allows you to back up your house full of Macs for $120 (£76) a year.

The clear winner here, however, is Livedrive, which for £3.95 a month enables not only unlimited storage, but also unlimited numbers of computers to be backed up. That is truly excellent value.

Results 1

Test two - Interface

group 2

One of the good things about all the tools in this test is that once they are set up they're all but invisible. Sure, you'll notice a hard disk spinning up and every now and again, and catch the toolbar notifications. In general, however, there's nothing to do other than sit back and let your data be backed up.

This, then, was a really tough call to make, as each of the backup utilities took a similar though not identical approach to organising and editing backups.

We docked a few marks from Livedrive and iDrive for a more fussy approach. Livedrive lists every single file being uploaded as it works, which is nice, but a simple progress counter would do. iDrive has a sync option that could easily confuse the non-techie user. But these criticisms are of the minor niggle variety.

Forced to make a decision, we'd err on the side of CrashPlan. It's just a little clearer than the others. That little bit is tiny, though, and not a major advantage over the competition.

Test 2