Chapter 1 - An Introduction to Virtualization

Abstract

Virtualization is defined as a framework or methodology of dividing the resources of computer hardware into multiple execution environments, by applying one or more concepts or technologies such as hardware and software partitioning, time-sharing, partial or complete machine simulation, emulation, quality of service, and many others. The objectives of any virtualization technology include adding a layer of abstraction between the applications and the hardware, enabling a reduction in costs and complexity, providing the isolation of computer resources for improved reliability and security, and improve service levels and the quality of service, etc. Software, referred to as a virtual machine monitor (VMM), controls use and access to the CPU, memory, storage, and network resources underneath. Server virtualization is the more dominant form of virtualization in use today. Implementations of server virtualization exist on, and for all, CPU platforms and architectures, the most popular being the IA-32 or x86. In its most basic form, storage virtualization exists in the assembly of multiple physical disk drives, or spindles, into a single entity that is presented to the host server and operating system, such as with RAID implementations. The true storage tier and its components were further masked by the introduction and adoption of storage area network (SAN) technologies. The most popular forms of network virtualization are: virtual LAN (VLAN), virtual IP (VIP), and virtual private network (VPN). Application virtualization, or software virtualization, is the newest member of the ever-growing virtualization family. It is a new approach to software management.