Differences between OpenVZ and XEN
XEN is the slightly more reliable virtualization software, a para-virtualization platform that creates virtual servers with almost exactly the same characteristics as dedicated servers (total isolation). A Xen VPS will run its own isolated kernel, load its own kernel modules, use fully dedicated virtualized memory, I/O and scheduler, and will be just as stable and extensible as a dedicated server. You'll never know that you're only using a virtual server -- for a small premium.
OpenVZ, on the other hand, is an operating-system-level virtualization platform that works in much the same way, but provides only a thin layer of virtualization on top of the underlying OS. All virtual servers on an OpenVZ node will share the same core Linux kernel--this is why OpenVZ only supports Linux OS templates--, and, consequently, will also suffer alike from issues like kernel crashes. Despite these small drawbacks, OpenVZ is more cost-effective, easier to understand, and usually performs much better for small virtual servers, due to having the extra resources available that a Xen VPS would be using to run its completely isolated environment.
Main Features of Xen Virtualization:
- Full root access.
- Supports Linux and Windows.
- Better Java performance.
- Resources (RAM, etc) are fully dedicated and private.
- Para-virtualized Linux kernel (i.e., full isolation).
- Direct access to loadable kernel modules.
- Swap space.
- Highly configurable.
Main Features of OpenVZ Virtualization:
- Full root access.
- OS-level virtualization.
- 'Burst' RAM and other extra resources available when nodes are underused.
- Upgrades can be applied on-the-fly, without reboots.
- More resources available due to lightweight virtualization.
- Simple network and disk setup.
- Access to most iptables modules.
If you are in doubt about which platform would be better for you, OpenVZ will most likely offer an easier-to-setup and more cost-effective solution, unless you know in advance that you will require specific kernel modules that OpenVZ may not support. At XenLayer t is easy to switch from OpenVZ to Xen at any time!