What's the difference between a private cloud and a virtual data center?

While virtualization is key to private cloud, the two are not synonymous. Features such as self-service provisioning will take your virtual data center to cloud.

What's the difference between private cloud and a virtual data center?

A private cloud is not really an alternative to a virtual data center. Instead, a private cloud infrastructure builds on the capabilities that virtualization already provides -- so virtualization is a critical underlying, or enabling, technology for the private cloud.

For example, virtualization provides a high level of system utilization, which also abstracts the workloads from the underlying hardware. This means the applications in each virtual machine (VM) are decoupled from the servers. Workloads can then run on any suitable virtualized server, and workloads can easily be migrated between virtualized servers with little, if any, discernible disruption in performance. These characteristics are absolutely essential to the cloud.

Virtualization is a critical underlying, or enabling, technology for the private cloud.

Although virtualization provides some significant benefits in workload provisioning, management and protection, it still requires direct support and intervention from IT staff. A private cloud infrastructure builds on the benefits of virtualization to add new features that reduce reliance on IT staff, including self-service, scalability and chargeback.

Self-service, or automation, allows users to provision and launch new virtual machines without the direct intervention of IT. For example, if a department wants to introduce a new server application, the department can set up the VM, allocate the computing resources, install the application and handle related tasks themselves rather than waiting for IT. In addition, users can scale the computing resources for their VMs. For example, if that new server application needs more -- or less -- storage, memory, CPU cycles and so on, the VM owner can scale those resources on demand.

And a private cloud also integrates reporting and chargeback features, which can automatically track computing resource use and bill the VM owners based on their utilization. In this way, VM owners feel the financial implications of their computing choices and are incentivized to make frugal computing decisions, such as eliminating unneeded VMs rather than continuing to pay for them each month.

However, a private cloud isn't always easy; it takes discipline and planning for business leaders to "own" their IT destiny. Cloud computing is the ultimate manifestation of utility computing, and businesses built on the traditional IT paradigm may not adapt well when forced to manage their own workloads and pay for them out of their own budgets.

About the author:
Stephen J. Bigelow, senior technology editor in the data center and virtualization media group at TechTarget Inc., has more than 20 years of technical writing experience in the PC and technology industry. He holds a bachelor of science in electrical engineering, along with CompTIA A+, Network+, Security+ and Server+ certifications, and has written hundreds of articles and more than 15 feature books on computer troubleshooting, including Bigelow's PC Hardware Desk Reference and PC Hardware Annoyances.

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