OpenVZ vs. Xen — Who is the Virtual Winner?

Virtualisation has become very important in the last few years.  With the weak economy and need to cut back in spending, virtual servers have become a mainstream tactic.  However, you need to choose the right software to split your physical server into private servers.  This can be tricky since there are several out there, but choosing the right one can help smooth over the setup process and get the configurability that you want.  Two of the most popular virtualisation programs on the market today are OpenVZ and Xen.  Now the question is, which one is better?

The Advantages of Xen

 Xen has always been considered a very reliable piece of software; it is open source and supports both Linux and Windows.  It is a para-virtualisation platform, which means that it creates virtual servers that almost perfectly mirror the physical server in all its characteristics.  Because of this, Xen creates very stable virtual machines that run within their own dedicated kernel modules and have virtualised memory that is fully dedicated.  Basically, it is almost impossible to tell that you’re are using a virtual server.

The Simplicity of OpenVZ

 OpenVZ is also open source, but it differs from Xen in a few distinct ways.  For one, it only works with Linux.  It is known as an operating system level virtualisation platform.  That is a very long title that basically means that it is similar to Xen, but the virtualisation only runs skin deep.  It does not have a dedicated kernel and you will have more control over the memory since it is not strictly dedicated to the virtual machine.

 

 So Which is Better?

 Both of these are very good virtualisation platforms, but for sheer reliability Xen is probably the better bet.  Both Xen and OpenVZ promise 256 MB of memory for each virtual machine; however, while Xen gives you exactly that, OpenVZ actually shaves off a little over 20 MB for allocation of other resources running in the background.  Also, OpenVZ has difficulties with kernel crashing since it only uses Linux templates.

This does not mean that Xen is always the better option; if you have a smaller company that does not need a lot of virtual servers OpenVZ is probably a better choice.  It is cheaper, easier to set up and can run much better since you have extra resources available for the server that needs it.  If you are just starting out and have a small company, OpenVZ is probably the best choice for you.  The best thing is that when your company grows and you need more powerful and configurable servers it is very easy to switch over to Xen.  This makes it a win for both platforms and for you.