Posted February 23rd, 2010
What Are VPS Technologies About?
Virtual Private Server (VPS) technology has become a popular alternative to more traditional shared hosting, as it offers far greater flexibility at a not much higher price. Unfortunately, the complexity of choosing the best virtualization technology for a given situation is usually far greater than are the much simpler choices required for a shared host. If you wish to use VPS technology but are unfamiliar with your available choices, here are a few commonly used virtualization technologies.
Generally speaking, there are two major categories of virtualization technology, each coming with its advantages and disadvantages. The first and simplest type works at the operating system level. When a new server is supplied, it comes with its own virtual space owing to a fresh OS install made in a subdirectory on the hosting system. 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.
There are disadvantages, however. 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 fully isolate and control resource use, so that particular servers consume only what have been granted.
Another virtualization technology involves emulating the underlying hardware on which an operating system runs, then installing it atop this 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. Having only one OS version on every single server would require high homogeneity, generally rarely acquired and more so in hosting, where flexibility is a key factor. 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, as such, 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 not confined to the limited shared hosting and expensive dedicated servers anymore. Understanding the virtualization landscape and available options is crucial in order to capitalize on this shift in hosting alternatives.
Tags: host, OS, server, technology, virtualization, web hosting
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