Virtual Private Servers
by Jimmy Martin
Virtual Private Servers (VPS), also known as Virtual Dedicated Servers (VDS) are the next step up from shared web hosting.
With a VPS, there are many websites sharing one server, as with shared hosting. The difference is that VPS websites are all isolated from each other. The server runs one copy of the web server software for each website.
Figure 3: Virtual Private Servers
The diagram in Figure 3 above shows a server running three virtual private servers. They are overseen by a "Hypervisor" program which allots the server resources to each VPS. As you can see, the memory and disk space are shared between the VPS's, however they do not have direct access, everything goes through the hypervisor. Each VPS is running its own Apache web server program, PHP programming language and MySQL database program.
Virtual Private Servers get their name because the software on each VPS thinks it has a private web server all to itself. This is an illusion created by the hypervisor program, almost like something from the Hollywood movie The Matrix. The programs are not actually running on a private server, but a Virtual Private Server.
This trick, called Virtualization, is not new to the computer world. IBM have been doing it with their mainframe computers for 40 years. However, it is a fairly recent arrival in the web hosting industry. It has quickly gained a foothold among sites which have outgrown shared hosting, but do not use enough resources to need a dedicated server all to themselves.
Next we will look at the Pros and Cons of Virtual Private Servers.