Virtual Private Server (VPS) technology has become quite a popular alternative to more traditional shared hosting, as it offers far greater flexibility for little extra cost. Unfortunately, it is a way much easier to choose between shared hosts than to pick the virtualization technique that would suit you best. If you wish to use VPS technology but are unfamiliar with your available choices, here are a few commonly used virtualization technologies.

Broadly speaking, there are two major categories of virtualization technology, each with its relative advantages and disadvantages. The simplest type is at the operating system level. When a new server is provisioned, a fresh OS install is made in a subdirectory on the hosting system, with the new server run in its own virtual space. The server and its processes are still visible to the main operating system, although they are separated from any other virtual installations. This way the users and processes of different servers do not interfere with one another.

This type of operating system virtualization has several important advantages. It generally needs fewer resources than other virtualization technologies, which makes it cheaper to manage. Servers of this sort can also generally be administered more easily and reliably, as they rely on the host’s kernel and are generally not prone to lockups introduced by using custom kernels with other virtualization solutions.

Still, there are also disadvantages. Operating system virtualization limits you to the kernel installed on the OS host, with no possibility for using either a different version or an entirely separate OS. One consequence of using OS-level virtualization is that upgrading OS to take advantage of new technologies may result impossible, since hosts each time have to justify upgrading all their servers. It is also difficult to thoroughly isolate and control resource use such that one user’s server does not consume more than their allotted share.

Another virtualization technology involves emulating the underlying hardware of an operating system, and then installing it on top of the virtual computer. Since virtual servers are for all purposes independent of the host’s hardware, they may support various kernel versions, or even completely different OSs.

This is one of full virtualization’s greatest advantages. Rarely is a computing environment homogeneous enough to justify a single OS version on every single server, especially in hosting situations where flexibility is a key selling point. Furthermore, most full virtualization solutions allow for the installation of custom kernels, making it possible to use VPS technology with modern device drivers and kernel level technologies still unfamiliar the provider.

Unfortunatelly, these advantages come at a cost. Full virtualization generally requires more system resources and therefore is more expensive to host. The ability to install custom kernels and operating systems introduces additional administrative overhead which, in the wrong hands, can render full virtual machines much less stable than are their OS-level counterparts.

Virtualization technology has revolutionized our concept of hosting as such. The choice is no longer confined to limited shared hosts or expensive dedicated servers. Understanding the virtualization landscape and available options is crucial in order to capitalize on this shift in hosting alternatives.