"The 'blue screen of death' is what the tech guy called it," says Chunta, a cancer researcher. "It was a freak-out moment."

So Chunta bought a new hard drive and installed it in his laptop, then tentatively reinstalled the cloud storage service backup software he'd purchased from Carbonite Inc. just a few weeks earlier. It took close to two days to restore everything, but he was able to rebuild his dissertation.

Chunta, who now has a Ph.D. in anatomy and cell biology, is one of a growing number of consumers who are choosing to use online storage services because they are relatively inexpensive, can automate the backup process and offer massive amounts of ubiquitous storage. But choosing the right cloud storage offering can be tricky: You could end up with a complicated user interface or tools that don't meet your needs.

Online storage services such as Carbonite and MozyHome, which is available through Decho Corp., an EMC company, are designed to provide simple continuous data protection so that each time a file is saved, the changes are replicated to the vendor's data center. But the services available can vary widely depending on the types of features they offer. For example, some can encrypt data in flight or adjust how much bandwidth a backup should use.