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Chapter 2. What is virtualization and migration?

2.1. What is virtualization?
2.2. What is migration?
2.2.1. Benefits of migrating virtual machines
This chapter discusses terms related to virtualization and migration.

2.1. What is virtualization?

Virtualization is a broad computing term used for running software, usually multiple operating systems, concurrently and in isolation from other programs on a single system. Most existing implementations of virtualization use a hypervisor, a software layer or subsystem that controls hardware and provides guest operating systems with access to underlying hardware. The hypervisor allows multiple operating systems, called guests, to run on the same physical system by offering virtualized hardware to the guest operating system. There are several methods for virtualizing operating systems.
Virtualization methods
Full virtualization
Full virtualization uses the hardware features of the processor to provide guests with total abstraction of the underlying physical system. This creates a new virtual system, called a virtual machine, that allows guest operating systems to run without modifications. The guest operating system and any applications on the guest virtual machine are unaware of their virtualized environment and run normally. Hardware-assisted virtualization is the technique used for full virtualization with KVM (Kernel-based Virtual Machine) in Fedora.
Para-virtualization employs a collection of software and data structures that are presented to the virtualized guest, requiring software modifications in the guest to use the para-virtualized environment. Para-virtualization can encompass the entire kernel, as is the case for Xen para-virtualized guests, or drivers that virtualize I/O devices.
Software virtualization (or emulation)
Software virtualization uses slower binary translation and other emulation techniques to run unmodified operating systems.


For more information and detailed instructions on guest installation, refer to the Fedora Virtualization Deployment and Administration Guide.