The key technology that makes VPS hosting work is virtualization. Your account is isolated onto its own “virtual machine” that, though it sits on a server with dozens or hundreds of other sites, functions within the boundaries of its own virtual environment. Thus, your VPS server is functionally equivalent to a privately leased dedicated server, save for a few minute differences.
Private Resources
All the resources assigned to your VPS hosting account are for your use only. For example, if you sign up for a virtual machine with a 1.13 GHz processor, 768 MB of RAM, 30 GB of disk space and 500 GB of bandwidth, these four resources become a permanent staple of your server that cannot be taken away from you — unless, of course, you fail to renew your lease.
Shared Hardware
While you own the resources, you have no ownership over the actual hardware. The server containing your VPS account may in fact house four 3.2 GHz processors, 8 GB of RAM, a 2 TB hard drive and TB upon TB of bandwidth, but it is the task of a virtual machine manager (VMM) or hypervisor to intelligently allocate portions of these components’ resources to multiple VPS machines.
The Hypervisor
The hypervisor or VMM separates your VPS “server” from all other “servers” on the server. It essentially makes your account panel think its on a unique, physical server, when it is in fact in a virtual environment. Accomplishing this feat requires that the VMM map and translate all requests between your VPS machine and the actual physical server. This is only possible with a virtualization-compliant CPU.
Root Access
Because your VPS server functions as its own physical device, you may treat it as one. This means you can access the virtual server’s core directory and make those adjustments you deem appropriate, i.e., delete unwanted system applications, install custom programs and upgrade the kernel. Such options are not available with shared web hosting, wherein you share a server but without the isolation of a virtual environment.
Putting It All Together
So in summary, in VPS web hosting, a hypervisor or VMM takes a certain amount of resources from the main physical server and sets it aside in a private virtualized space known as a VPS server. You gain the benefit of dedicated resources and the added flexibility of being able to customize your software applications, but you pay a far cheaper rate than you would if you were to rent out an actual dedicated server.
