What is a Virtual Private Server?

A Virtual Private Server (VPS) is an entire operating system that runs within another operating system. It will share system resources like the CPU and RAM with other users but the resources are allocated in such a way that you cannot tell that the system has anyone else on it, much like a dedicated server. So resources are usually setup in such a way that each hosting client is only allowed to use an allocated percent, meaning that resources assigned to you will always available to you. Each virtual server looks and acts like a dedicated server.

So for instance, there may be a server with 2GB RAM, 100GB of disk space and 2 x 2GHz processors with 10 VPSes on it. Each one is guaranteed to have access to 200MB RAM, a disk space limit of 10GB, and an effective CPU of 400Mhz.

There are a number of virtualization technologies, which make this all possible. There are commercial companies such as http://www.vmware.com VMWare, http://www.xensource.com/ XEN.

Like an emulator, VMware software provides a completely virtualized set of hardware to the guest operating system. VMware software virtualizes the hardware for a video adapter, a network adapter, and hard disk adapters. The host provides pass-through drivers for guest USB, serial, and parallel devices.

In essence, virtualization lets you transform hardware into software. Use software such as VMware ESX Server to transform or “virtualize” the hardware resources of an x86-based computer—including the CPU, RAM, hard disk and network controller—to create a fully functional virtual machine that can run its own operating system and applications just like a “real” computer.

Multiple virtual machines share hardware resources without interfering with each other so that you can safely run several operating systems and applications at the same time on a single computer.

VPS Hosting plan

VPS hosting plans fill the gap between entry level web hosting plans which offer specific services (such as PHP/MySQL, or Perl/CGI) with a limited amount of disk space on a shared server, and co-location, where you own and manage the hardware and simply rent “rack space” and an Internet connection at a data center. If you are outgrowing a shared hosting plan, but aren’t ready for the financial commitment of co-location, a VPS hosting plan could be the ideal middle ground.

VPS hosting plans have the following key advantages:

* Allows hardware to run at a higher utilization rate.
* They are cheaper since usually they have less power costs than one physical server
* Root access means you can install and configure any programs you want. Want to run PHP with PostgreSQL instead of MySQL - go ahead, install it.
* You can host an unlimited number of web sites through Apache’s Virtual Hosts.
* You can host other services, such as a mail server, an FTP server, or any other type of server you want.
* You can use the server for backup, file storage, or anything you need.
* Virtual Private Servers are also more secure since even as you share the memory and CPU time, you are allocated your own file system. If a website on the server is hacked, the hackers will only have access to that particular file system and would not harm the other websites. A VPS is also much cheaper than a dedicated server.

However, VPS hosting plans have the following disadvantages:

* Since you are in control of the server, you are also responsible for all installation, maintenance, security and updates. If you are inexperienced with administering a Linux Server, and are not willing to learn as you go, this may be a big drawback.
* While a VPS hosting plan gives you an entire operating system of your own to work with, you are still sharing hardware resources (CPU, RAM, etc.) with other VPSes on the same host server. Therefore, if performance is key, or you are running RAM intensive programs, you may be better off with co-location.

Getting to the Root

So what do you get with a VPS account? Well, the one thing you do get is root access to your server. It means you have complete control, can install any programs you want, and do anything you choose. However, it also places the responsibility for configuring and implementing in your hands. If you’re not comfortable with this, stay away from VPSes.

Most VPS plans have a number of “disk images” to choose from with different distributions (such as Debian or Fedora Core) with default configurations. You specify which disk image you want, and it will be configured on your VPS in a matter of minutes. Once you are set up with an account, you are then given root access via ssh, and can login and customize your server, install new software, remove unwanted software and update existing software as needed.

Choosing a VPS hosting company

Here are a few pointers of things to look out for.

Know the details of your hardware resources

* What are the specifications of the host server? (RAM, CPU, Network throughput, etc.)
* How many VPS instances run on the host server you will be on? This is important because you are effectively sharing the host server’s resources with these other VPSes.
* How is resource contention handled - in other words, what happens if all the other VPSes on your host server are running CPU/RAM intensive processes? Do you have a dedicated minimum amount of RAM/CPU/Network usage? If so, how much?
* Ability to upgrade or downgrade the VPS service if needed.

Know the details of your Virtualization technology:

* What’s the underlying OS: Linux, FreeBSD, Windows? If Linux, what distros are offered?
* How are hardware upgrades handled? Let’s say you start out with a basic plan that offers 64MB dedicated RAM and 2GB disk space. Six months from now, you realize you need more RAM and more disk space. What are the additional costs and what is the procedure for allocating the additional resources?

Conclusion: If one has a small budget but big ideas then VPS would be ideal choice.

Article Authored by Deric.

Author, Deric, is a Systems Engineer with SupportPRO. Deric specializes in Cpanel and Linux servers. SupportPRO offers 24X7 technical support services to Web hosting companies and service providers.