Server virtualization technology effectively gives your physical server computers multiple personalities. With virtualization, administrators can run several separate environments on one machine, to make full use of its capacity. A thin layer of software called a hypervisor creates and manages the different virtual machines. Each virtual machine is isolated from the others, so if one of them is attacked, fails or is otherwise compromised, the others stay safe and unaffected. Each one runs as a separate, fully functioning server.
Server virtualization technology also allows you to install multiple operating systems on the same machine. Since there is no primary operating system for a virtual server, you can install Unix and Windows side-by-side for testing purposes or if you need a feature unique to one of the operating systems. Server virtualization allows for a higher density of servers but does not increase the raw computing power of the physical server, it only makes sure that none of the power goes to waste.
Instances created from server virtualization are called virtual private servers. You can offer these individually created servers to users so that each user can essentially have their own environment to play with. This is especially beneficial in web hosting – offering virtual private servers allows system administrators to make the most of their resources. Many users never use a server to its full capacity, so sharing the physical resources of the host computer ensures that the server can be used to its full potential.
IT departments favor switching to server virtualization technology because it allows them to outsource the physical location of their servers while still allowing them control over the system. However, server virtualization works best with small to medium projects as the power needed for large systems can exceed the capabilities of the physical server.
Server virtualization technology lets system administrators install the different types of web or application servers they need to host their system. HTTP, FTP, DNS LDAP and Active Directory servers can be installed side by side on multiple virtual servers in order to provide redundancy and data backups.
Software licensing can be an issue for server virtualization. As far as the software company is concerned, each virtual server on the physical machine is a separate system and will require a separate license and support agreement. This can quickly add up so where possible some administrators use open source software.
When evaluating the feasibility of server virtualization technology, consider the size and type of server setup you need. High volume systems run best on dedicated physical servers as do systems that require a high percentage of storage or memory resources at any given time. When implemented properly, server virtualization technology can give a much needed improvement to your server systems.