Virtualization is the logical separation of the request for a service from the physical resources that actually provide that service, and is also one of today's hottest IT topics. The primary reasons for the popularity of virtualization today are the increasing speed and capabilities of today's off-the-shelf processors, falling hardware prices, and the ubiquity of networks that offer the capability to connect almost anything to anything else. These combine to provide higher performance and higher capability systems at a lower cost, providing plenty of CPU cycles and processor capabilities to handle any extra layer of abstraction that virtualization might introduce.
The loudest virtualization-related buzz surrounds different approaches to two topics, namely virtual storage and virtual machines:
Virtual storage, as the name suggests, prevents users and system administrators from having to know the physical devices on which their data is stored because you access that storage through logical device, disk, or volume names. The physical hardware that supports these logical or virtual disks can be located on separate disk drives, storage devices, or even on physically distinct computer systems. Common virtual storage mechanisms such as logical volumes were introduced in Chapter 4 and discussed in more detail in Chapter 24.
Virtual machines ...