There's a war on over which of these two approaches will eventually come to dominate enterprise computing. Most of the arguments involve control and security versus costs. But when you get right down to the brass tacks, it's always going to come down to what it always does in every enterprise application debate: performance.
Providers of cloud computing services will argue that when it comes to performance, they have the inside track given their ability to build data centers using the latest and greatest IT infrastructure. The challenge facing the internal IT organization looking to build a private cloud is how to match those performance levels at an acceptable level of cost. Of course, many would argue there's more to it than that, but when you look at the ability to secure information in the cloud and the manageability tools becoming available, it's hard to say with absolute certainty that private clouds have an inherent advantage when it comes to security and manageability.
Of course, there's nothing magical about public cloud infrastructure, either. The companies that build public clouds leverage the same IT infrastructure as internal IT organizations, which is why you see vendors such as NetApp hosting events to market the same types of storage technologies to builders of both public and private clouds. Once upon a time, vendors sold service class and enterprise-class technologies, but those distinctions are becoming increasingly irrelevant as internal IT organizations morph into internal IT service providers.
The two real advantages that many public cloud providers have today are economies of scale in terms of acquiring equipment and highly disciplined IT procedures. The advantage an internal IT organization has is its ability to provide customized services and the simple fact that not every application workload needs blinding performance. More often than not, application workloads have varied levels of performance requirements, which means that a one-size fits all approach to cloud computing might not be the most economical way to go. Furthermore, internal IT organizations are getting better at running their operations like a business by the day.
Just about every IT industry professional, as evidenced by the attendees at this week's Cloud Computing Expo in New York, is equally divided about whether public or private cloud computing will win out, which is a sure sign that both models will probably thrive. The only real question is to what degree will each be used in connection with what types of application workloads. And despite the protestations of all the various cloud computing advocates, only time will really tell us the answer.