Virtual Private Servers (VPS) are a virtualization of the server operating system that splits a single physical server into multiple virtual servers. This practice was common in old mainframes but new operating systems, especially Linux, have made the practice much more common in the Web Hosting industry.
VPS fills a void between shared web hosting and a full-blown dedicated server and many hosting companies actually run their shared hosting business from VPS accounts. It allows root-level access to clients without physically dedicating the server. This allows the user to “virtually” control his entire server environment but it is cheaper than a dedicated server because the server owner can “lease” the server into multiple virtual environments for many clients. Thus, if a server platform costs a few hundred dollars per month for the hosting company to operate, it can sell the resources to dozens of clients operating in Virtual Private Server environments and charge them $20-$90 per month per client.
VPS is a great way to “cut your teeth” on the way to a dedicated server platform. I provide pro bono web hosting to non-profits and ministries and hosted about 50 different “clients” on my VPS solution from JaguarPC until I took on a couple of very “busy” sites. The VPS was ideal as it cost only $80 per month for 45 GB of storage and about a few hundred GB/month of bandwidth. Better, with full root access, I was able to “sandbox” the environment of an actual server. I could start and stop the web server, mail server, ftp server, etc. I could add and delete accounts en masse. I could add custom applications and was even able to run two instances of Apache on the same VPS account. For all intents and purposes, it was “my server”.
There is only one problem with a VPS – it is still a “shared” service. The CPU and the memory are not completely your own. Web hosts will advertise a minimum RAM and CPU availability depending on the level of VPS that you purchase but it is still one server with several clients accessing resources. It is not usually the normal request of HTML pages that really slows a server down as these tax memory and the CPU very little. Rather, it is applications that use mySQL (like WordPress or Drupal) and it is anti-Spam solutions like SpamAssassin that end up bringing your virtual environment to its knees. The message here is that one ought to know the nature of the clients they will be hosting and how CPU and Memory intensive their use of resources will be. It’s not a matter of buying the “high end” VPS solution and you may need a dedicated server for the task.
The above is not to recommend against VPS – if your resource requirements do not rise to the level of needing a dedicated server then spending over $150 per month when you can spend $50 per month for the same “virtual” service is a waste of money. There are even some VPS providers that are recognizing a desire among clients to have an even more “muscular” VPS and are offering more powerful VPS solutions, which primarily entails guarateeing that there will be fewer clients on the same machine.
Thus, VPS is a great option for anyone needing the ability to host multiple sites that needs or desires complete control of the server environment. It gives you greater performance and greater control than a shared hosting solution but is less expensive than a dedicated server solution.