OpenVZ or Xen – Which should I choose?

A common question we get asked is “Should I choose OpenVZ or Xen? Which is better? What are the differences?” OpenVZ and Xen are both different beasts and each platform is better for different applications – the trick is choosing the right one for your project. Hopefully this post should help clarify a few things!

Closer look


When most people think of virtualisation, they think of guest OS floating about within a host OS (a la VMware and virtual machines,), and they aren’t far wrong: this is basically how most virtualisation platforms work. OpenVZ isn’t virtualisation in the traditional sense of the word. The architecture is based around a single, modified GNU/Linux kernel that is shared between all of the containers on a node, in a similar way to FreeBSD jails and thus is more like containerisation than virtualisation. The end result is a lightweight platform that is best suited for basic applications such as web hosting or email.


Xen is closer to ‘proper’ hardware virtualisation in that all of the VPSs on a node are completely separate and each have dedicated resources allocated to them. Also, since each VPS has it’s own kernel, each VPS can run a different OS and additional kernel modules can be installed. Our Xen VPSs are paravirtualised which means you can run any OS that supports this such as Linux, BSD and Solaris among others.

OpenVZ is normally sold with burst memory in addition to the allocated RAM, whilst you’ll typically see Xen bundled with swap. So what is the difference? Burst is where your VPS has the ability to use memory that is not being used by other VPSs on the node, up to your allocated burst limit. Swap is dedicated paging space on disk that the Xen VPS has access to when the normal RAM allocation is used up.

In a nutshell


  • Best for basic applications like web hosting and email
  • Single application hosting (not RAM intensive)
  • Behaves more like FreeBSD jail
  • Can be affected performance-wise by other containers on the node
  • Limited iptables support
  • OpenVZ containers must be Linux, although they can be different distros
  • OpenVZ is fast and lightweight


  • Better for gaming servers
  • Better for demanding applications (Like Java for instance)
  • Behaves more like a dedicated server
  • Dedicated resources
  • Securely isolated VPSs
  • Swap not burst

Of course if you are still unsure then please feel free to get in touch and we’ll be happy to help you choose a suitable platform for your project.

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