Server virtualization is the act of sectioning one server into multiple parts. The solitary virtual environments go by several names, but the most common is virtual private networks (VPN). Other terms used to describe these divisions include containers, guests, emulations, and instances. In most cases, each portion of the server is able to run its own autonomous operating system while all of the portions run off of the same underlying hardware.
There are three common methods of server virtualization:
Virtual Machine Model
Paravirtual Machine Model
Virtualization at the operating system
Virtual and paravirtual machine segmentations allow for multiple operating systems. Virtualization at the operating system only allows a single operating system for all users.
Similarly, virtual and paravirtual machine models function using a host / guest paradigm whereas virtualization at the operating system works somewhat differently.
Dividing a single server into multiple virtual private networks during virtualization can be viewed as part of a larger trend in IT which includes workload management, network virtualization and storage virtualization. These sorts of activities all serve as components in the grand scheme of creating systems that can self-manage themselves referred to as autonomic computing.
The Advantages of Server Virtualization
The primary rationalization for splitting up a server is consolidation of small servers onto a bigger one. This is such a common occurrence due to the cost benefits associated with such a migration. Also, a migration has no effect on the operating systems or applications used.
Migrating several mini-servers onto a larger one reduces the amount spent on:
Another advantage of server virtualization is that it gets rid of server sprawl, a situation where multiple under-utilized servers consume more space and resources than they require for the tasks they perform. This increases the amount of server availability as well as the amount of work that can be done by that server.
An additional positive is the simplicity involved with replicating servers. Standard virtual server builds greatly reduce the amount of time necessary to deploy a new server.
Server virtualization also compensates for the amount of activity each user performs. This autonomic computing aspect provides efficient designation of resources and maximum efficiency.