Figure I.1 The process of virtualization involves a virtualization layer called a hypervisor that separates the physical hardware from the virtual machines. This hypervisor manages the virtual machines' access to the underlying hardware components.

For those just beginning the journey to a virtual server environment and for those who have already established their virtual infrastructures, the reasons for using virtualization can vary. Virtualization offers many significant benefits, including server consolidation, rapid server provisioning, new options in disaster recovery, and better opportunities to maintain service-level agreements (SLAs), to name a few. Perhaps the most common reason is server consolidation.

Most servers in a datacenter are performing at less than 10 percent CPU utilization. This leaves an overwhelming amount of processing power available but not accessible because of the separation of services. By virtualizing servers into virtual machines running on a hypervisor, we can better use our processors while reducing rack space needs and power consumption in the datacenter.

Depending on the product used to virtualize a server environment, there are many more benefits to virtualization. Think of the struggles IT professionals have had throughout the years and you'll gain a terrific insight into why virtualization has become such a popular solution. The simple process of moving a server from a datacenter in Tampa, Florida, to a datacenter in Atlanta, Georgia, is a good example of a common pain point for IT pros. The overhead of removing an 80-pound server from a rack, boxing it, shipping it, unboxing it, and placing it back into another rack is enough to make you want to virtualize. With virtual machines this same relocation process can be reduced to simply copying a directory to an external media device, shipping the external media device, and copying the directory back to another ESX implementation. Other methods, such as virtual machine replication and full and delta images of virtual machines, can be taken with third-party tools.