Thursday, March 14, 2013

Virtualization- Basic Meaning

Hi everyone. In my previous post i talk about three basic requirement for Cloud Computing to take hold in the market. First among them was Virtualization. From long time I want to talk about Virtualization in detail but didn't get time. Today I am free, so lets dig deeper in understanding basic meaning of virtualization and How it came to picture?

Virtualization is not the technology of 21st  century. It was used by IBM for its Mainframe Computers in 1960's. Mainframe computers has multiple resources to consolidate these different resources and make them act like single resource requires Virtualization. Cloud Computing utilize this idea more comprehensively which makes it first requirement for implementation of Cloud Computing. First look at few definitions of Virtualization.

According to Wikipedia “Virtualization in computing, is the creation of a virtual (rather than actual ) version of something , such as hardware platform, operating system, a storage device or a network device.

Gartner stated that, “ Virtualization is abstraction of IT resources in a way that masks the physical nature and boundaries of those resources from resource user. An IT resource can be Server, Client, Storage, Networks, Application or Operating System

What we pull out from these two definitions is Virtualization is conversion of Physical to Logical of everything and anything and logical doesn't know about actual physical resource. Just remember Physical to Logical. One more thing if you simply search on web for definitions on virtualization you may find some definitions saying virtualization is running multiple operating System on single hardware resource. This is not definition of virtualization it is a type of virtualization i.e. Server Virtualization. So, don't confuse yourself when you find these type of definitions. Virtualization can be done of anything i.e. Network Virtualization, Storage Virtualization etc.

These are all formal definitions and explanations. I hardly understand any concept with formal definition. I need examples and detailed definition to grab a concept or technology. If you say we started using virtualization with mainframe computers that may be wrong. Actually we were using this technology in our day to day life in one or another way, for example.

Suppose, I have a big shop. No one want it on rent because it is very large and no one can afford that much rent also. What we do in our day to day life. We create a partition in middle of shop and make it into two shops. Both shops are rented to 2 different shopkeepers. Each shopkeeper thinks he rented the whole shop. Actually floor and ceiling is shared. What owner of big shop did in reality–  He VIRTUALIZED the big shop and created two small virtual shops. Same concept we are using for IT resources. Physical resources (Server, Storage, Network) are shared among different virtual machines but each virtual machine is isolated from each other.

Now to do Server Virtualization we need a software known as Hypervisor. The most crucial piece of any virtual infrastructure is the hypervisor, which is what makes server virtualization possible. A hypervisor creates a virtual host that hosts virtual machines. It is also responsible for creating the virtual hardware that VMs will use. If you look up the term hypervisor, the definition will likely say that a hypervisor is an “abstraction layer.” That’s because it abstracts the traditional server operating system (OS) from the server hardware. Another way of saying this is that the hypervisor decouples the OS from the hardware. Your server OS no longer has to be tied to physical hardware and the newly virtualized server can be hardware-independent and containerized inside a virtual machine. There are two types of Hypervisor as shown in Figure below:


Type 1 hypervisor is installed directly on physical server hardware, thus replacing the existing OS. This is the most efficient design, in that it offers the best performance as well as the most enterprise-level data center features. Examples are VMware vSphere and Microsoft Hyper-V.

Type 2 hypervisor is installed and “hosted” by the existing OS and Virtual Machines are known as Guest OS. This is less efficient but enables you to keep existing applications already installed on the host OS. Examples are VMware Workstation, VMware Fusion and Windows Virtual PC.

Hope you now understand basic meaning of Virtualization. If you gave a deep thought on this concept you can easily see at many places we use this concept in our life.

See you all soon and till then happy Virtualizing.

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