When we speak of "cloud computing" we are typically referring to some sort of service which we use through the internet. However to most technologists a cloud tends to mean something a little bit more specific and more closely tied to a server.

Up until a few years ago you would buy a special type of computer called a "server" and install your operating system or other software on it.

But today you can procure a "virtual server" without having to purchase any hardware at all. These virtual servers typically reside across multiple physical servers, and can even be moved quite easily from server to server.

In other words, yesterday's concept of a server as a piece of hardware is now being replaced by the increasingly common concept of a server as a piece of software, aka a virtual server. In fact, the actual hardware you used to be required to purchase is becoming less relevant.

Cloud computing then is often thought of as the procurement of these types of virtual servers through the internet.

There are a number of providers of these virtual servers and some of them are even quite large. Amazon Web Services is said to be generating close to a Billion dollars a year in revenue by selling use of these virtual servers. Companies like CloudSigma, GoGrid and Rackspace are all also very well known. And, of course, everyone has heard of Microsoft; they offer this same service, and they call it Azure.

One thing that has become painfully clear to a lot of people is that the details of each service matters. How each of these companies set up their hardware, how they provision operating systems, how they provide secure access to the server, and what tools they provide to remote manage the systems; these issues and more vary greatly between vendors, and make a significant difference when you are looking to purchase a cloud server.

In fact, few of these companies disclose the mechanisms that underly their cloud services for a variety of good reasons. Recently, an executive at Microsoft gave a presentation describing at a high level how their Azure service actually works.

This talk gives a fascinating look into the layers of software that need to be created by a provider to credibly provide a flexible cloud service.

But still a lot of details are left to question.

In the long run, the reality is that as consumers we probably don't need the details. We need guarantees of performance and stability, and we need control over key routing and transport issues, or at least some guaranteed acceptable service assurances.

However, until cloud servers are commonplace, and until the space matures, any heavy consumer of one of these cloud providers needs to take some time to understand the mechanics and corresponding limitations imposed by the provider. Otherwise, you may get an unwelcome surprise.

This was originally posted on the Central Penn Business Journal Gadget Cube.

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