The question I’m currently struggling with is:

Is there really such a thing as a private cloud?

The term “Private Cloud” is proving attractive to quite a few CIOs. The private cloud idea is to implement a “cloud architecture” within the data center on a sensible collection of (possibly new) resources. You then deploy applications into that architecture. Such applications will then be “cloud ready” and you may, at some future point, be able to deploy those applications into commercial clouds.

Assuming you adopt an architecture that matches and can interface with some provider(s) of Infrastructure-as-a-Service (IaaS) there’s lots of sense in this:

• You may be able to use the IaaS as expansion space.
• You may be able to use the IaaS specifically for software testing.
• You may use the “private cloud” as a staging area before moving applications into the cloud.

Having said that, the private cloud will have little relevance to any Platform-as-a-Service or Software-as-a-Service operations, because (with very few exceptions) they run proprietary environments. (This may change in time, but don’t start counting chickens yet.)

So what does a private cloud look like? Well, it looks like a set of virtualized resources, because that’s what it is. And that means it looks like a whole set of consolidated servers – hopefully with a good set of management software for managing the virtual resources. Conceptually, there’s little difference  between a private cloud and a set of virtualized resources. A “private cloud” may include some interface software, which connects to an external IaaS service. But that’s it really. Private Cloud is marketing speak; although you might want, need and gainfully employ what lies beneath.

So let’s look at the graph. First thing to say is that the Y-axis is logarithmic. And that means that the curve is an awful lot steeper than it looks; much much steeper. The Y-axis shows user populations from 1 to a billion. If the axis wasn’t logarithmic, it would need to be about 6000 miles long, not the 3 inches long, that it is.