March 01, 2010, 1:18 PM — One of the biggest decisions IT managers have to make is how and where to run data center applications. Fortunately, there are multiple choices that lower costs and increase business agility, including server virtualization, internal clouds, public clouds and external private clouds.
Many IT organizations are taking advantage of these options. Server virtualization is currently being used by more than 70% of enterprises to reduce costs, and cloud computing is being used or planned for use by more than 10% of corporations, according to Antonio Piraino, research director at Tier1 Research.
It can be confusing and difficult to determine which cloud environment to use (see sidebar below for descriptions of the most popular types of clouds). There are few, if any, guidelines, and each company will almost certainly have a unique discussion about its choices because each will have varying requirements and different views of what cloud computing means.
To take advantage of the new opportunities afforded by cloud computing, IT organizations have to learn the differences between server virtualization and various types of clouds, and understand the risks associated with using each execution environment in terms of the characteristics of various applications.
What is a cloud?
One may wonder why there's an interest in cloud computing when server virtualization is already providing significant cost savings by reducing the number of physical servers that enterprises buy. But it's not the same thing at all.
Different clouds to choose from
There are basically two types of clouds: public clouds and private clouds. Cloud types can generally be characterized by their location (on-premises or off-premises) and the perceived degree of security that they provide.
A public cloud is one in which a cloud service provider makes resources such as servers, storage, networking and, possibly, applications available to users over the Internet. Public clouds are off-premises by definition. A customer's applications may be running in an intermingled style on the same physical server as another customer's applications, meaning public clouds are multitenant. Public cloud services, such as Amazon's EC2, are usually offered on a pay-per-usage model -- you pay for what you use.