Cloud versus cloud: A guided tour of Amazon, Google, AppNexus, and GoGrid

Who wouldn't want to live in a "cloud"? The term is a perfect marketing buzzword for the server industry, heralding images of a gauzy, sunlit realm that moves effortlessly across the sky. There are no suits or ties in this world, just toga-clad Greek gods who do as they please and punish at whim, hurling real lightning bolts and not merely sarcastic IMs. The marketing folks know how to play to the dreams of server farm admins who spend all day in overgrown shell scripts and impenetrable acronyms.

To test out these services, I spent a few days with them and deployed a few Web sites. I opened up accounts at four providers, configured some virtual servers, and sent Web pages flowing in a few hours. Our choice of four providers wasn't as scientific as possible because there are a number of new services appearing, but I chose some of the big names and a few new services. Now, I can invoke Joni Mitchell and say I've looked at both sides of these services and offer some guidance.

The first surprise is that the services are wildly different. While many parts of Web hosting are pretty standard, the definition of "cloud computing" varies widely. Amazon's Elastic Compute Cloud offers you full Linux machines with root access and the opportunity to run whatever apps you want. Google's App Engine will also let you run whatever program you want -- as long as you specify it in a limited version of Python and use Google's database.

The services offer wildly different amounts of hand-holding, and at different layers in the stack. When this assistance works and lines up with your needs, it makes the services seem like an answer to your prayers, but when it doesn't, you'll want to rename it "iron-ball-and-chain computing." Every neat feature that simplifies the workload does it by removing some switches from your reach, forcing you into a set routine that is probably but not necessarily what you'd prefer.

After a few hours, the fog of hype starts to lift and it becomes apparent that the clouds are pretty much shared servers just as the Greek gods are filled with the same flaws as earthbound humans. Yes, these services let you pull more CPU cycles from thin air whenever demand appears, but they can't solve the deepest problems that make it hard for applications to scale gracefully. Many of the real challenges lie at the architectural level, and simply pouring more server cycles on the fire won't solve fundamental mistakes in design.

By the end of my testing, the clouds seemed like exciting options with much potential, but they were far from clear winners over traditional shared Web hosting. The clouds made some things simpler, but they still seemed like an evolving experiment.