By Matthew Dublin

It was a bit telling when, during the large general session talk that kicked off this week's Cloud Expo 2011 in New York City, speaker Bill Zack, an "architect evangelist" with Microsoft, enthusiastically asked the audience of roughly 1,000 plus attendees:

"Show of hands — how many of you people believe that the cloud means infinite compute?"

A few dozen hands went up.

"Alright! Show of hands — and how many of you people believe that the cloud means infinite storage?"

No hands that I could see went up.

After the sound of crickets died down, Zack recovered by saying, "Well, it all depends on what your definition of 'infinite' is..."

Indeed. And it also depends on what your definition of cloud computing is, unless, of course, you're OK with the idea of meaning as a moving target. That there is still such malleability among cloud zealots when it comes to that definition is directly connected to the overblown expectations and the confusion surrounding cloud computing. Zack was, of course, aware of this fact and, after finishing his pitch for Windows Azure, he wrapped up his talk by telling the audience to not become despondent. Keep an eye out for the National Institute of Standards and Technology, he said, which is still hard at work nailing down its definition of cloud computing once and for all.

In an attempt to steer clear of any nebulousness and with an eye toward the pragmatic, Adiascar Cisneros, a professional services manager at Racemi, gave a talk on "on boarding" which is cloud-speak for moving existing software applications onto a cloud. In a packed ballroom at the Jacob Javits Convention Center, Cisneros started off his talk by looking at various use cases for determining when a private cloud, public cloud, or hybrid cloud, is the best choice.

When one audience member asked him what was the difference between hosting your own applications on servers and a private cloud Cisneros basically said that a private cloud was like hosting your own applications on in-house servers just...better.

Possibly anticipating the confusion, Cisneros wisely took pity on us all and offered up a simple formula for determining which applications to move to the cloud and onto which cloud architecture to move them. The basic guidelines are:

If your application needs elasticity, users require it to be highly available, and you're also looking to reduce capital expenditure costs for operation, look to the public cloud, like Amazon's EC2.

However, if security is paramount, you are dealing with regulatory and compliance issues, you need top-notch performance, and you have already put a lot of money into developing this software (referred to as "sunk costs), then a private cloud is for you.
At the end of his talk, Cisneros plugged Racemi's DynaCenter solution, which provides automated configuration and migration of a cloud set-up from private to public, public to private, or either to hybrid and back again. DynaCenter supports Linux, Unix, Windows, VMware, Xen, and Hyper-V and the user is supposed to see nothing as an administrator moves the cloud around from a dissimilar hardware or cloud providers.