The primary benefits of virtualization are green and green; green as in consuming less energy, and green as in saving money. Virtualization benefits users of both personal computers (PCs and Macs) and data-center servers by reducing total expenses. Virtualization lets you run multiple operating systems simultaneously on a single machine (computer or server hardware unit). Through virtualization, one operating system, usually called the host, lets one or more virtual operating systems, usually called guests, run on the same machine. Fewer machines cost less, consume less energy, and have lower administrative and maintenance costs. For more information, see Virtualization 101.

Benefits of Virtualization in Personal Computers

If you use virtualization at home, or in a small business, you save money and desk space. For example, if you need to run both Windows and Linux operating systems, you need not buy two PCs because virtualization lets you run both operating systems simultaneously on a single PC.

Dual booting (or multibooting) is not the same as virtualization. For example, you can set up your PC for dual booting either Windows or Linux. Each time you start (or restart) your PC, you must choose to boot either Windows or Linux. After you boot your PC, it can run only your booted operating system until you either turn off or reboot your PC. In contrast, virtualization lets you run both Windows and Linux operating systems simultaneously.

Note: Although virtualization software for personal computers technically supports multiple guest operating systems, running more than one guest operating system might degrade performance too greatly. For example, your host operating system might need 1 GB RAM (Random Access Memory), and your guest operating system might need 512 MB RAM.

Virtualization software for personal computers includes Windows-host, Mac-host, and Linux-host virtualization.

Windows-Host Virtualization – Windows host virtualization lets you run two operating systems simultaneously on a Windows PC. Your host operating system is a Windows version (such as XP, Vista, or Windows 7). For your guest operating system, you can choose Mac OS X, a separate Windows version, or a Linux distribution (such as Ubuntu or Red Hat). Windows-host virtualization software includes:

• VirtualBox for Windows Hosts
• Parallels Desktop 4 for Windows and Linux

Mac-Host Virtualization – Mac-host virtualization lets you run two operating systems simultaneously on a Mac computer. Your host operating system is Mac OS X. For your guest operating system, you can choose a Windows version or a Linux distribution. Mac-host virtualization software includes:

• VirtualBox for OS X Hosts
• Parallels Desktop 4.0 for Mac
• VMware Fusion

Linux-Host Virtualization – Linux-host virtualization lets you run two operating systems simultaneously on a Linux PC. Your host operating system is Linux. For your guest operating system, you can choose Mac OS X, a Windows version, or a separate Linux distribution. Linux-host virtualization software includes:

• VirtualBox for Linux Hosts
• Parallels Desktop 4 for Windows and Linux

Benefits of Virtualization in Data Centers

Most data centers do not use their full processing capacities. Virtualization lets a single machine (server) support many multiple applications and networks. For data centers, the benefits of virtualization include:

• Saving physical space. Data centers are running out of space because they continually need to add physical servers. Virtualization, through its ability to run multiple software virtual servers on a single hardware server, relieves corporations and organizations from the constant need to build more data space.
• Consuming less power. A smaller data center, running more software systems on fewer servers uses less energy. Therefore, virtualization is good for both the environment and corporate profitability.
• Reducing operating expenses. Virtualization lowers payroll costs by diminishing the need to add too many system administrators and other support persons as data center capacity increases.

Note: Although data-center virtualization does improve corporate efficiency and profitability, it is not a manager’s one-minute miracle. Reaping the benefits of virtualization requires careful planning, training, and installation. Beyond business and technical issues, you need also pay attention to legal requirements. For example, if you currently require separate software licenses for application copies running on separate physical servers, you will need to maintain those licenses after you have moved the application copies to virtual servers.