CrashPlan stands out from the competition in terms of the variety of options it offers users. To begin with, its client is available for a wide variety of computers, from Macs and Windows PCs to Linux and Solaris systems. There are also apps for accessing stored data for Apple iOS and Android devices, but not for BlackBerry phones.

There are also a number of different plans. The free version actually doesn't offer online backup, but instead allows you to back up to other computers, for example, a system belonging to a friend, or a system at work. It's an interesting twist that can lessen the chances that your data will disappear, but might put it in too many hands. I'm not sure I'd want my data sitting on someone else's computer, although CrashPlan does encrypt it.

The paid versions allow you to back up your data to CrashPlan's online servers. The CrashPlan+ service that I used offers unlimited storage for $50 (£30) a year; there's also a plan that limits capacity to 10GB for half as much, but both are limited to a single computer.

The unlimited family package gives you backup for up to 10 computers for $120 a year. The company offers a full-featured trial for 30 days.

CrashPlan has a central interface that shows the status of your backups and how many files are queued up. It also has places to click for restoring files, for determining where the backups will be stored and for making configuration changes. CrashPlan doesn't visually mark files for backing up as Mozy and Carbonite do. The software does have an excellent log that shows all tasks performed.

By default, the software gathers up key personal files like music, video and desktop files for backing up, but ignores Windows and system files. However, you can manually add any file type to the backup, including system files.

After its initial backup, CrashPlan continually looks for changes in your system's files and adds those that it finds to its next backup. CrashPlan does this behind the scenes as you use your computer; I didn't notice any slowdown of my system as a result. By default, the system will send backups every 15 minutes, but that interval can be changed; you can do an incremental backup at any time as well.

CrashPlan has a screen that shows a progress bar with an estimate of how long it will take to finish (except, of course, when it is working in the background). The service can also back up the contents of an external hard drive.

CrashPlan uses 448-bit key Blowfish encryption (the free version uses 128-bit Blowfish encryption). Unlike the other applications reviewed here, which have deadlines after which deleted files are removed, files backed up to CrashPlan and then deleted from your hard drive are never removed unless you do it manually, according to the company.

CrashPlan colocates its servers at several data centres throughout the US, but doesn't mirror backups.

Test results

Uploading backup data to CrashPlan's servers was slow, it stopped several times during the process, once for a little over an hour. As a result, it took 4 hours and 7 minutes to save 321MB during the initial backup.

Archiving the entire C: drive took four days, 20 hours and five minutes, four times longer than the next closest service, Norton Online Backup.

I was able to back up the system's C: drive to a 250GB Western Digital external drive in 2 hours and 6 minutes, midway between Norton Online Backup and Mozy.

The service's ability to perform a 25MB incremental backup took just 1 minute and 3 seconds, the fastest of this gang of five. Like the others, CrashPlan searched for a lost file quickly, at 2.3 seconds, and restored it 35.6 seconds.

OUR VERDICT

CrashPlan offers some innovative services and the ability to save your backups on other computers. However, uploading backups to CrashPlan is slow, which can be a problem.