What comes to mind when you hear the phrase “cloud computing”?  Despite all the benefits, do you get a vague feeling that somehow you’re going to be handing over control of your system or your data to someone else?  That’s not surprising.  The common understanding of a cloud system is called a “public cloud,” where anyone can sign up and start uploading programs and data alongside anyone else.  Of course, there are security safeguards in place, but you share the cloud infrastructure and hardware with others.

There are other options for cloud computing.  One of these is a private cloud.  The most recent draft copy of “Cloud Computing Synopis and Recommendations” from NIST (The National Institute of Standards and Technology of the US Dept. of Commerce) defines a private cloud like this: “The cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on premise or off premise.”

This opens new possibilities.  Suddenly cloud computing is not something “out there.”  It can be managed on-site by your own IT staff, using your own hardware.  Or you can outsource the operation and still have exclusive use of the cloud computing resources.  Either of these kinds of private clouds (on-site or off-site) can be used to support real-time systems.  Each has its own inherent advantages and drawbacks.

An on-site private cloud deployed at a single location does not rely on outside networking, and is easier to secure.  But the upfront costs are higher, especially if you build and maintain it yourself.  Also, there are fewer resources available for “cloud bursting,” or handling sudden, heavy computing loads when you are using an on-site cloud.  So you lose some of the key advantages of a cloud system.

An off-site private cloud, on the other hand, would be less expensive to implement up front, and would be more flexible in providing additional resources on short notice.  But it would run partially, at least, on external networks and more effort would be needed to implement security.

In a way, we can view on-site and off-site private clouds as sort of stepping stones towards a public cloud.   As you move up the steps, your costs go down and flexibility increases.  But to gain those benefits, you need to depend more on external networks or the Internet, and to keep a close eye on external security.

One approach to trying out cloud computing for a real-time system could be through implementing a private cloud.  This would give an opportunity to gradually gain valuable experience in cloud computing.  For example, you might want to experiment first with an on-site system, and once the kinks are worked out, move to an off-site private cloud.  Then sometime down the road, you could move to a public cloud.

Or, there’s another possibility–a hybrid cloud.  We’ll talk about that next week.