Server Virtualization

In computing, virtualization is the process of presenting a logical grouping or subset of computing resources so that they can be accessed in ways that give benefits over the original configuration. This new virtual view of the resources is not restricted by the implementation, geographic location or the physical configuration of underlying resources. Commonly virtualized resources include computing power and data storage.

A good example of virtualization is modern symmetric multiprocessing computer architectures that contain more than one CPU. Operating systems are usually configured in such a way that the multiple CPUs can be presented as a single processing unit. Thus software applications can be written for a single logical (virtual) processing unit, which is much simpler than having to work with a large number of different processor configurations.

Virtualization is about running an Operating System (the guest OS) on the top of another OS (the host OS). This technique enables running several virtual machines with different OSes at the same time on the same hardware. VMWare, MacOnLinux, and Xen are examples of virtualizer software. Virtualization requires guest OSes to be built for the host machine processor. It should not be confused with emulation, that do not have this requirement: When an OS runs on the top of a virtualizer, its code runs unchanged on the processor, whereas an emulator has to interpret to the guest OS code. MAME or Basilisk are examples of emulators. Binary compatibility is another different feature: it is the ability of an OS to run applications from another OS. For instance BSD systems are able to run Linux binaries.

Avenues for Virtualization software

1. MS Virtual Server 2005 - http://www.microsoft.com/windowsserversystem/virtualserver/default.mspx

2. VMWare – www.vmware.com
3. XenSource - http://www.xensource.com/ (from Xen Open Source community)


References:
http://www.virtualization.info/
A great article with an introduction to Virtualization [kernelthread.com]
Microsoft Virtual server Road Map :
http://www.entmag.com/reports/article.asp?EditorialsID=87


Advantages of Virtualization

1. Increase utilization of existing Server hardware
2. Easy maintenance
3. Help in Business continuity and Disaster Recovery initiatives


Shrini