Cloud computing has matured to the point where most organizations are now in the cloud at some point or are considering moving. The benefits in terms of savings (fewer hardware and software investments), scalability and agility are well documented.

Public Clouds

Public clouds provide commercial services such as Google Apps, storage, sales force automation and other Software-as-a-Service (SaaS) compatible applications over the Internet in real time. By sharing IT infrastructure with others and benefiting from flexible resource allocation, companies are realizing significant savings and faster time to market to deploy new services and bring proprietary applications online.

The downside? By using a public cloud, you have less control. That’s why some IT managers want to bring the benefits of an internal external cloud by delivering metered services exclusively through internal resources.

Private Cloud

The private cloud takes all the advantages of its public counterpart and puts it inside the corporate data center. According to Wikipedia, it “mimics cloud computing on a private network and offers the ability to host applications or virtual machines within the company’s own host set.” Private clouds provide “utility computing benefits – sharing hardware costs, the ability to recover from failures and the ability to rise or fall depending on demand.” The key technologies needed are virtualization for maximum scale, flexibility, and hardware utilization, automation for fluid workload allocation and authentication to restrict unauthorized access.

But unlike a public cloud, you have to build and manage the infrastructure yourself, and thus, won’t see upfront savings for capital expenditures and management expenses that come with a publicly shared resource pool. Given that economics has been the main driver behind the appeal of cloud computing, why would you want to bring the cloud in?

Why Go Private?

The main reason is safety and control. For starters, in a public cloud, you effectively put all your eggs in one basket. If the cloud declines or vendors go out of business, you’re out of luck. With a private cloud, you provide your own services and control access through an internal Web portal.

By storing data in a data center, you eliminate outbound transfer costs, gain direct control over Service Level Agreements (SLAs) and enable better compliance with the various rules surrounding privacy, protection and data storage. In fact, some government regulations and corporate governance mandates stipulate that certain types of customer data must be on -premises, making the use of public clouds unsuitable for some applications.

The Best of Both Worlds

A recent IDC survey revealed that 55 percent of IT executives said they would rather use a private cloud over a public offering but not for all applications. The line between the two is blurred and fortunately, public-private hybrid models are a hot new trend. Mike Vizard of IT Business Edge notes in his blog that “cloud computing will routinely become more hybrid with application workloads dynamically shifting to and from between internal and external clouds.

However, when that happens, the difference between public and private cloud infrastructure will start to crumble and the term cloud computing itself may simply disappear. To accelerate that development, new technologies that allow you to build virtual private clouds on top of public infrastructure are emerging.

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