Virtual Private Server
From Website Hosting Wiki
A virtual private server – or VPS – is a single physical web hosting server that is partitioned into multiple parts with each part acting as if it was a sole dedicated server. It appears and has the capabilities of a single server including its own operating system. Each VPS can be independently rebooted even though it is on a single physical server unit. This method of partitioning a single server has been previously used in large mainframe computer systems and has recently resurged with the onset of virtualization software and technologies for the smaller computers of today.
When the web hosting company first boots up a VPS server, the physical server boots up first and then runs a software program that boots each partitioned virtual server. The virtual server acts like an emulator and the virtual servers are typically booted from a disk image. Virtualization comes in two varieties. Software based virtualization shares the same server kernel and uses the main node resources. Hardware based virtualization actually partitions the servers resources and it tends to be more secure than the software virtualization.
Virtual private services are commonly used to bridge the gap between dedicated hosting services and shared web hosting services. They allow the user the independence of a server that acts as if it is dedicated to their website and only their website without having to pay for a dedicated web hosting physical dedicated server. Customers who use a VPS system has access to the operating system on the partition and can install just about any software that runs on the operating system that is installed. Firewalls, anti-virus clients, and virtualizers usually do not work with VPS systems and while the web hosting service may restrict what you can run or install, they are usually more lax about the items put on the server than shared hosting services. The processor time, RAM, and disk space are usually limited, but still better than shared hosting.
VPS are commonly used to test website updates or look for possibly insecure public services. Detailed testing can be conducted on one part of the server while the website remains live until the bugs are worked out of the updates. They are also sometimes used to run software that has known security flaws on it so that the programs do not endanger the rest of the server. The programs can still be used, but the server and all of the files on it are not left open to hacking or other security risks.
Each web hosting service company works differently and they may offer virtual dedicated servers to their customers as an additional web hosting service. They are usually offered in three different packages. Managed hosting gives the customer the tools to monitor and control the virtual machine that their website is hosted on. The web hosting company manages the server itself and maintains it to keep it running properly. Unmanaged hosting has the web hosting company providing only minimal services such as SSH consoles and reboots. This type of hosting is less expensive than managed hosting services. Unmetered hosting is similar to unmanaged hosting but customers are given a fixed bitrate that they cannot exceed in a month’s time.
