Is cloud computing just hosting by another name?

Without proper service guarantees, companies remain reluctant to adopt cloud services. But if those guarantees are in place, is it still cloud computing?

Here's the problem with cloud services that offer computing and storage on demand.

Commodity purchase of a service over the Internet, without negotiating a one-off deal, is part of what defines cloud computing. But Amazon, the company that best fits that description for on-demand infrastructure, also provides no real SLA to speak of. That means businesses will use it for dev and test, temporary compute-intensive apps, and so on, but not for any critical operations.

[ Take a look inside Amazon Web Services with InfoWorld's Test Center | For a unique perspective on cloud computing and its implications, check out whurley's cloud computing blog. ]

So what if you want a SLA that means something? Well, you won't go to Amazon. In most cases you'll pick up the phone and call a sales engineer at a hosting provider, then negotiate features and configurations and pricing until you figure out a solution just for you. Of course, you pay for that. Yet more and more traditional hosting providers are wrapping offerings in the cloud envelope, just to capitalize on the buzz.

Some have been doing more than others to make themselves cloudlike. Rackspace, for example, runs a traditional hosting business but also offers Mosso, its cloud infrastructure service. Mosso is cheaper than conventional hosting and doesn't dedicate specific hardware to customers. Plus there's some self-service: Instead of uploading and replicating virtual machines, as you do with Amazon, you use Rackspace's Web tools to build your stack on a Rackspace machine -- then replicate away.

In Rackspace's case, though, you get an SLA similar to the basic plan offered by the company's hosting service: If you have a problem, Rackspace promises to fix it in an hour, and it will refund 5 percent of your monthly hosting fee for every half hour of downtime.

Recently I asked Rackspace's chief strategy officer, Lew Moorman, what exactly was cloudy about Mosso's infrastructure. For one thing, he said, the company offers "multitenanted storage" -- that is, your files and those of other customers may sit side-by-side on the same drive. For another, Rackspace had to develop its own virtual file-based storage software, which includes authentication, to scale across commodity hardware. Moorman said he would have "preferred it if he didn't have to" develop it, but that all such other systems were tied to specific platforms (such as EMC's Atmos).

Mosso customers get a standard LAMP stack. Sometime this year, he says, the company will also offer Windows "in a fully supported way." In that same time frame, he says, the company will open a kind of app store for server stacks built on open source software.

But ultimately, says Moorman, cloud computing by his definition is "just the next generation of hosting." That means lower prices, relatively lightweight SLAs, and -- if VMare's vApp takes hold -- maybe even some portability down the road. But for enterprise customers, at least, the difference between old-fashioned hosting and the new-fashioned cloud is smaller than it appears.