Cloud computing has become a convenient and cost efficient way for companies to store data while using remote, shared servers located in the “cloud.” But what is cheap and easy, isn’t always safe.

Take Amazon.com, for example. The company branched out into the cloud computing business five years ago and has since offered computing resources to thousands of businesses — most of them small with a low likelhood of having data backup and recovery services (bad risk management!).

Last week, that lapse in risk management was felt after Amazon.com’s cloud services crashed, disrupting web services for companies as large as Pfizer and as small as FourSquare.

The Amazon interruption, said Lew Moorman, chief strategy officer of Rackspace, a specialist in data center services, was the computing equivalent of an airplane crash. It is a major episode with widespread damage. But airline travel, he noted, is still safer than traveling in a car — analogous to cloud computing being safer than data centers run by individual companies.

As of this morning, many of the affected sites are back online, though “some historical data might be missing,” according to Chartbeat, a company that monitors the online presence of websites.

The risks of cloud computing is not a new topic among business owners, CIOs and risk managers — far from it. For years, talk has circled regarding privacy, compliance and legal issues. One recent article in PC World examines the risks of cloud computing. It covers topics such as who accesses your data, regulatory compliance and (probably most importantly) data loss and recovery.

Corporate cloud computing is expected to grow rapidly, by more than 25% a year, to $55.5 billion by 2014, according to International Data Corporation estimates. And as the popularity of cloud computing grows, so will the potential risks. With that in mind, companies are wise to evaluate such perils and plan for what could go wrong with such a modern technology marvel.