Characteristics of Virtualization in Cloud Computing

By Judith Hurwitz, Robin Bloor, Marcia Kaufman, Fern Halper

Any discussion of cloud computing typically begins with virtualization. Virtualization is using computer resources to imitate other computer resources or whole computers. It separates resources and services from the underlying physical delivery environment.

Virtualization has three characteristics that make it ideal for cloud computing:

  • Partitioning: In virtualization, many applications and operating systems (OSes) are supported in a single physical system by partitioning (separating) the available resources.

  • Isolation: Each virtual machine is isolated from its host physical system and other virtualized machines. Because of this isolation, if one virtual-instance crashes, it doesn’t affect the other virtual machines. In addition, data isn’t shared between one virtual container and another.

  • Encapsulation: A virtual machine can be represented (and even stored) as a single file, so you can identify it easily based on the service it provides. In essence, the encapsulated process could be a business service. This encapsulated virtual machine can be presented to an application as a complete entity. Therefore, encapsulation can protect each application so that it doesn’t interfere with another application.

Applications of virtualization

Virtualization can be applied broadly to just about everything that you could imagine:

  • Memory

  • Networks

  • Storage

  • Hardware

  • Operating systems

  • Applications

What makes virtualization so important for the cloud is that it decouples the software from the hardware. Decoupling means that software is put in a separate container so that it’s isolated from operating systems.

Forms of virtualization

To understand how virtualization helps with cloud computing, you must understand its many forms. In essence, in all cases, a resource actually emulates or imitates another resource. Here are some examples:

  • Virtual memory: Disks have a lot more space than computer memory. Therefore, with virtual memory, the computer frees valuable memory space by placing information it doesn’t use often into disk space. PCs have virtual memory, which is a disk area that’s used like memory. Although disks are very slow in comparison with memory, the user may never notice the difference, especially if the system does a good job of managing virtual memory. The substitution works surprisingly well.

  • Software: Companies have built software that can emulate a whole computer. That way, one computer can perform as though it were actually 20 computers. The application consolidation results can be quite significant. For example, you might be able to move from a data center with thousands of servers to one that supports as few as a couple of hundred. This reduction results in less money spent not only on computers, but also on power, air conditioning, maintenance, and floor space.