Virtualization Renaissance

ing from embedded to server systems. Enterprises commonly employ virtual LANs and private networks (VLANs, VPNs). System area networks use storage virtualization to simplify the management of complex, heterogeneous storage configurations. Virtualization technologies encompass a variety of mechanisms and techniques used to decouple the architecture and user-perceived behavior of hardware and software resources from their physical implementation. Central to resource virtualization is the introduction of an indirection layer below the execution environment seen by applications and operating systems. A key component of virtual machines, the virtual machine monitor (VMM), provides a layer between software environments and physical hardware that is programmable, transparent to the software above it, and makes efficient use of the hardware below it. Through indirection, VMMs and similar networking and storage resource virtualization techniques provide the capability of multiplexing, on a single physical resource, many virtual systems that are isolated from each other. The insertion of a lower-level abstraction below existing abstractions is in marked contrast to the common approach of constructing a higher-level abstraction on top of the Virtualization technologies encompass a variety of mechanisms and techniques used to address computer system problems such as security, performance, and reliability by decoupling the architecture and userperceived behavior of hardware and software resources from their physical implementation.