Virtualization – A Quick Tutorial
Just the mention of the word “Virtualization” in a Technical meeting or IT seminar will get you enough 
attention and interest from the people around you. Even then I have not found a basic tutorial on the subject of Virtualization which just explains it and lets me choose where to go from there . So, I have written one, this is what I will call “Pre-Reading before you go onto bigger concepts in VIRTUALIZATION“.
What is Virtualization? (Quick and Dirty)
Wikipedia Says: Virtualization is a term that refers to the abstraction of computer resources. Virtualization hides the physical characteristics of computing resources from their users, be they applications, or end users.
EDTB Says:
Virtualization is a concept of putting servers, storage, applications and users on different logical places which reduces dependencies on each others. This Indeed provide a higher probability that one doesn’t screws up another.
This is done to create an illusion of interoperability and save [money,physical space, time and environment mostly in the same order] where user does not care where application is stored and application does not care where it is data is stored as long as its accessible, storage is logical and can be scaled up or down and server are for a change used for all its worth.
A Brief History
Virtualization is actually, a concept has been around for almost 50 years and real life implementation proofs of virtualization techniques have existed for close to 45 years. Virtualization is fairly mature technology. It just that the right time for Virtualization is -Now. Virtualization has been in the mainframe markets for quite some time now.
IBM started to explore virtualization in and round 60’s as a way to implement “time-sharing” on the IBM 7044. By creating multiple virtual images of the main machine (7044) they were able to allow multiple users access to the same memory and resources of the main machine through their virtual images.
This led to the development of the VM/370, a major advancement in the mainframe arena for their System/370. It allowed for multiple “copies” of the hardware that ran as virtual sessions while the virtual machine monitor (VMM) ran directly on the real hardware. The VM/370 was one of the most successful offerings in IBM history. The concepts and techniques established in the late 60s and early 70s are still used today on their large mainframe systems. These same concepts we have for the virtualization techniques we use today on our Intel and AMD based servers.
Due to the declining cost of servers and storage and the drift from the mainframe systems, virtualization lost its value for a while 1980s and early 1990s. Distributed computing and client-server applications were the hot topics of the time, and many companies saw huge cost savings in switching to low-cost x86 based systems.
Even though the cost of hardware was falling fast during this time period, few companies looked at the whole TCO (Total cost of Ownership) of having thousands of separate servers running for different application and huge amounts storage being wasted (underutilized) because of this. Finally we had to pay salaries and save the environment also.
Then came along VMware ,VirtualBox and Xen !!!
Virtualization Split Wide Open
Virtualization is a performed on various resource across the system ecosystem. Here are a few.
Server Virtualization
Running multiple logical servers on a single physical machine is a popular way to saving on hardware costs and makes backup and administration easier.
Why Virtualizes Server?
Several market and technology trends have converged to create “ideal conditions” for virtual server adoption. CPU underutilized: Server hardware performance continues to increase faster than the ability of applications to use it. Blaming Microsoft’s DLL hell: Most System Administrators do not run multiple applications on a single system image because they dread DLL conflicts and other incompatibilities will cause systems to crash. With wide Market adoption of Microsoft ® Windows ® servers with x86 CPUs has radically driven down the cost of computing.
Storage Virtualization: SAN (Storage Area Network) solution is used to provide storage for virtual servers, rather than depending on the hard disks in the physical server.
Why Virtualizes Storage?
Storage systems suppliers are addressing these challenges by introducing layers of logical abstraction between the physical ports on an array, the blocks of data on specific sets of disks, and the volumes or files that servers and applications need to access.
With the use of NAS storage with its own file system is a form of virtualization that uses files rather than blocks as the basic virtualized element. Virtual tape libraries represent another form of virtualization that is widely used in mainframe environments and, more recently, in the open systems world as well.
Note: “Storage virtualization will become key to greater adoption of server virtualization soon server and storage lines will blur. We are moving from server centric infrastructure to storage centric infrastructure”
Desktop Virtualization: Running client operating systems in a VM for training purposes or for support of legacy software or hardware not to forget playing the Mario, islander, Contra…. Also Time to time using Microsoft office from Apple Mac !!! Virtual testing environments, which provide a cost-effective way to test new software, patches, etc., before rolling them out on your production network.
Application Virtualization: Separate application configuration layer from the operating system so that applications can be run on client machines without being installed. This is good for Demo’s , trial runs etc but no more 30 Days period 
.
Presentation Virtualization
You can run an application in ‘A’ location and control it from ‘B’, with processing being done on a server and only graphics rendering and inputs captured at the client end. Virtualization programs are available, depending on exactly what you need to do. You might want to run a virtual machine on top of your desktop operating system, running a different OS, either to try out a new OS or because you have some applications that won’t run in one of the operating systems.
Have Fun!!!
Look Maa No Windows Only
There are many virtualization technologies and many of them run on operating systems other than Windows. You can also run non-Windows guest operating systems in a VM on a Windows host machine. VMWare can run on Linux, and Microsoft previously made a version of Virtual PC for Macintosh (but did not port it to the Intel-based Macs). Parallels Desktop provides support for running Windows VMs on Mac OS X. Parallels Workstation supports many versions of Windows and Linux as both host and guest. Parallels Virtuozzo is a server virtualization option available in both Linux and Windows versions. Other virtualization solutions are Xen (now owned by Citrix), Q, an open source program based on the QEMU open source emulation software, for running Windows or Linux on a Mac, Open VZ, for creating virtual servers in the Linux environment.
Roll Back the – Blue Screen of Death
Backing up virtual machine images and restoring them is much easier and faster than traditional recovery methods that require reinstalling the operating system and applications and then restoring data. The VM can be restored to the same physical machine or to a different one in case of hardware failure. Less downtime means higher availability and greater worker productivity.
Mount Wikipedia
You can mount the Wikipedia as a virtual filesystem. Download WikipediaFS . This is a mountable Linux virtual file system that enables you to deal wikipedia as any other Drive [View and Edit Wikipedia (or any Mediawiki-based site) articles as real files].
Caveat
Licensing requirements: As far as licensing is concerned, most software vendors consider a VM to be no different from a physical computer. In other words, you’ll still need a software license for every instance of the operating system or application you install, whether on a separate physical machine or in a VM on the same machine.
Make sure your applications are supported : Issue that needs to be addressed is whether the application vendor will support running its software in a VM. Because VMs use emulated generic hardware and don’t provide access to the real hardware, applications running in VMs may not be able to utilize the full power of the installed video card, for example, or may not be able to connect to some of the peripherals connected to the host OS.
RAM it up: It its obvious, but the more virtual machines you want to run simultaneously, the more hardware resources you’ll need on that machine. Each running VM and its guest OS and applications will use RAM and processor cycles, so you’ll need large amounts of memory and one or more fast processors to be able to allocate the proper resources to each VM.
Can Operating Systems currently detect if they’re running in a VM?
Yes, they can. Right now they do it through a couple of techniques – direct hardware fingerprinting and inferred hardware fingerprinting.
Direct hardware fingerprinting is pretty straightforward. Virtual Machines have predictable hardware profiles, so you can just query for “virtual hardware” that’s only available in VM’s and can’t easily be changed. The Virtual PC Guy describes this approach here
After this, Please read the logical next step : What is DeDupe.
Resources
Gartner Identifies Six Best Practices Companies Should Consider Before They Virtualize Their Servers
Virtualization Overview
Virtualization Technologies Overview
State of the Storage Virtualization Market 2008
The Storage Virtualization Landscape
Open source and virtualization: Twin trends to drive customer Value
Server Virtualization and Trends and its latest trends
Trends in Data Protection and Restoration technology
Seven disadvantages of server virtualization
Virtualization Defined – Eight Different Ways
Virtualization Jobs Blog
Virtualization: What’s In It For You?
VirtualBox
ClassicGaming
Virtualize AND dual-boot the same Windows on your Mac
Windows on Mac, Simultaneously
Virtual Appliance Marketplace
5 reasons why you should use VirtualBox, instead of VirtualPC or VMware
Microsoft Sets Virtualization Free
Convert Physical Machines to Virtual Machines – Free!
Virtualize Windows on Linux? Microsoft Says Servers First
MacIntel in a VMWare Session
Xen
As far as Desktop Virtualization is concerned, give a look into MokaFive’s LivePCs also. They are proving itself to be the pioneer in Virtual Desktops for Business and Personal use. MokaFive gives users the freedom to work on any hardware, any OS, and from anywhere.
You may check the technology at their website:
http://www.mokafive.com/