Server Virtualization

Server virtualization means partitioning of a physical server into various virtual servers. It is used to expand the server resources. In the server virtualization, the resources of the server are hidden from the users, and software is used to divide the physical server into various virtual environments called a virtual server or private server results in the dedication of one server to perform a single application. In other words, server virtualization is the division of the physical server into various virtual servers.

Usage of Server Virtualization

Server virtualization technique is a technique that is used in web-servers, which minimize the cost of web-hosting services somewhat having a separate system for each web-server; multiple virtual servers can run on the same system.

The uses of server virtualization are:-

• To centralize the server administration
• Improve the availability of server
• Helps in disaster recovery
• Ease in development and testing
• Make efficient use of server resources

Approaches used for Server Virtualization

The approaches used for server virtualization are:

1. Virtual machine model
2. Para-virtual machine model
3. Operating system (OS) layer virtualization

1. Virtual machine model: - It is based on the host-guest paradigm, where every guest runs on a virtual model of the hardware layer. This technique of virtualization offers a guest operating system to run without any change, and it needs real computing resources from the host and for this hypervisor software or VM is needed to coordinate instruction to the CPU.
2. Para-virtual machine model: - ThePara-virtual machine model is also based on the host-guest paradigm, and it is also a used virtual machine monitor. In the Para-virtual machine model, the VMM did the modification in the guest operating system’s code, which is called “porting.” Just like a virtual machine, the Para-virtual machine is also capable of executing multiple operating systems. It is used by both Xen and UML.
3. Operating system layer virtualization:-Like virtual machine model and Para-virtual machine model, it is not based on the host-guest paradigm. In this type of virtualization model, the host runs on a single operating system kernel as its core part and transfers its functions to each of the guests. The guest also uses the same operating system as the host. The distributed nature of architecture removes system calls between layers and hence minimizes the overhead of CPU usage. In this, it is must That each partition remains isolated from its neighbors because any failure or security breach of one partition will also be affected by the other partition.

Advantages of Server Virtualization

1. Cost reduced:- Server virtualization lessens the cost  because less hardware is needed for server virtualization.
2. Independent restart:- Every server can be rebooted independently, and that reboot won’t affect the working of another virtual server.