Go OpenVZ or Go Xen for VPS?

Paravirtualization-capable hypervisors include  Xen, Virtuozzo, Vserver, and OpenVZ (which is the open source and development version of Parallels Virtuozzo Containers), but the most common types used are OpenVZ and Xen.  If you are a first time VPS user, you might want to know which one to go for: OpenVZ or Xen?

OpenVZ is an operating system-level virtualization technology based on the Linux kernel and operating system.

Xen is a virtual-machine monitor for IA-32, x86-64, Itanium and PowerPC 970 architectures. It allows several guest operating systems to execute on the same computer hardware concurrently.

– Practically speaking, OpenVZ is better than Xen

In summary, OpenVZ is an system-level virtualization platform while Xen is a hardware-level para-virtualization platform. So which one is better?

OpenVZ servers virtualizes directly on the system-level; it operates under the OS with other accounts on the same server, and it has lower overhead, which usually translates to better performance.

On the other hand, even though Xen is still based on virtualization technology, it gives you more of a dedicated server behaviors.  Each Xen servers will have its own Linux kernel and virtualised memory, disk I/O; so it is more stable.  However, all these features might compromise a bit of performance juice.

So technically, OpenVZ is more efficient than Xen.

– Should you choose OpenVZ or Xen

Rockia.com is hosted on Linode’s Xen platform;  if OpenVZ is better than Xen, why would I choose Xen as my virtualization platform?  The reason is “to avoid overselling”.

Example:

Since OpenVZ is a system-level virtualization, VPS provider could open as many accounts as they want in a system.  If the physical sever has 16GB memory for example, it’s absolutely normal that there will be about 20 concurrent VPS users, each with 1GB of memory (from the pool);  and these VPS servers will be quite stable too.  However, I am sorry to say, lots of VPS suppliers will open more than 30 VPS accounts, still with 1GB of memory for each account (from the pool).  This is what we call “over-selling”;  VPS users won’t notice any difference in the system profile, but during the actual use, the performance will be much lower than expected.

Since Xen is based on hardware-level, if 1GB of memory is assign to each user, then 16GB of memory could only be assign up to 15 users or so.  There is no way a VPS suppliers could virtualize more than 16 users if each of them has 1GB of memory.  There for the performance is guaranteed.

Post Note:

If you are a first time VPS user, you might want to try OpenVZ platform first because usually VPS servers based on OpenVZ is cheaper than those based on Xen platform.

However, if you prefer Xen platform, I do recommend Linode to you.  This is the VPS provider Rockia.com is on and I found it extremely stable; if you also would like to support Rockia.com, you can use the following referral code to sign up for Linode.

http://www.linode.com/?r=fd71913368eb7c8ef638f842af2b45d49a2966a7

or use the referral code: fd71913368eb7c8ef638f842af2b45d49a2966a7

I also have collected a table of VPS providers with the virtualization platform:

(Note: No one nor any affiliate companies pay me to write this post, so all the links below are posted as text and not hyper links.)

Since one dedicated server could usually host more VPS accounts using OpenVZ platform than those using Xen, so the cost for each account is lower and OpenVZ is more popular.

For more VPS based one Xen, you can visit: http://wiki.xensource.com/xenwiki/VirtualPrivateServerProviders