‘The Cloud’ is today’s hot new buzzword. It’s used to market just about every new technology you can think of from server computing to cloud-connected coffee machines. This begs the question, “what is Cloud really?”. To answer this we need to look at the history of technology just prior to the rise of the term ‘Cloud’. Before the ‘Cloud’ became popular we had the practice of hosting or co-location. Companies would host websites, email, and other common Internet services in third-party data centers freeing up I.T teams to focus on other objectives.

More and more services starting being hosted by these third-party providers. The practice of running company servers in a provider’s data center, originally called co-location, became more popular too. Around that time the term ‘Cloud’ started to be used to refer to the practice of hosting one’s infrastructure elsewhere. This is where we get the first of two definitions for the term ‘Cloud’. Cloud can simply refer to my equipment or services in someone else’s data center.

As this trend grew several problems became apparent. Not everything could or should be moved to the Cloud. Hybrid clouds became more common as the cloud strategy was evaluated and tested. There became a growing need to move computing services back and forth and to allow seamless communication between local and hosted assets. Virtualization was already well-established practice by this time. To keep up with the demand for greater flexibility network switches and other infrastructure became virtualized as well. A given network might exist in both on-premise and in the Cloud allowing machines to move back and forth easily, even automatically.

A change had to be made to the type of infrastructure and its design to support this type of flexibility. Local networks that were capable of communicating and integrating with cloud provider networks came to be known as ‘Private Cloud’. From a technological standpoint the term makes sense. In essence, you are running a cloud technology on a local network and connecting it to the greater Cloud. One can’t help but notice the inherent problem with the first definition of Cloud. If Cloud is putting my services and assets somewhere else then what does it mean when I bring them back?

The technology however has to lead to the second definition of Cloud. With traditional local networks, one would scale-up servers and needed. When an application ran too slowly it might be time to add more processors or RAM to the server. In a virtualized environment one might grant more shares to the affected server or even dedicate a host to it. Eventually, though you run out of the ability to scale up.

Cloud technology makes it easy to spin up new servers and add resources. It can even be done automatically without human intervention. The Cloud introduces a different way to scale. Instead of a single server being boosted with upgrades, many servers can now be pooled together to better manage the load. Work can be spread out across servers, data centers, and even continents.

This approach to system demand is called scale-out. The second definition of Cloud then applies to this approach. By leveraging the dynamic nature of modern cloud technology, and by designing applications to leverage the scale-out approach, systems can be scaled to meet almost limitless demand.

The traditional cost model also changed drastically. Infrastructure, both hardware, and software are now bought on a subscription model. The cost scales up and down with demand. The Cloud model has nearly eliminated upfront capital expenditures from the network. Most vendors are moving to this model. Even hardware vendors, like HP, offer subscription sales allowing customers to pay for the hardware they need while being able to spool up additional hardware without having to wait for it to be shipped and ordered.

Ultimately the term ‘cloud’ is still evolving. As you can see it applies to both strategy and technology. At the heart of cloud computing is its scale-out dynamic nature. Cloud has moved beyond it’s early meaning of hosting and co-location. Today Cloud can even exist in a private network.