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Page history last edited by PBworks 16 years, 1 month ago

Thanks for coming to my presentation!

I hope it was useful for people thinking about virtualizing some of their machines.

We have been using OpenVZ for a few months and I have only good things to say about it.


While I haven't take the time to clean up my presentation, I found this one which covers pretty much the same things.


If you are thinking about virtualization, I suggest that you understand the 3 types of virtualization to narrow down your focus (as explained in the presentation).


It boils down to:

  • If you need to run multiple different Operating Systems on the same machine you will need to go with VMWare server/ESX/Player, Parallels Desktop, QEMU, etc. The achievable density (i.e how many VMs you can run on one server) of the VM will be rather low and you will suffer a pretty big performance impact.
  • If you only want to run multiple Linux instances on the same machine, your density will be very high by going with a single kernel virtualization solution. In Linux OpenVZ & VServer are options & there are similar efforts for FreeBSD (jails) & Solaris (Zones) giving you the same density.


Some points from the discussion:

  • Redhat is pushing Xen pretty hard (shipping with RH 5), but it doesn't seem to be stable yet.
  • OpenVZ has been proven to be rocksolid for us with neglible performance impact (Most of the time we can't measure it. The worst we have seen is 10% in a mixed Enterprise App load environment.)
  • OpenVZ is now also used for us in performance testing as it makes setting up an environment really easy. VMs are between 200-400MB and can be easily canned by using something like tar. This gives you nice packaging & archival options making it easy to start with a clean environment.
  • OpenVZ only allocates the memory actually used for each VE machine.
  • Creating a VM from scratch and booting it up takes typically 2-9 seconds (on a 2xCPU Opteron box, mirrored SATA drives) in OpenVZ.


Thanks for coming & let me know if you have questions.

Erich Nachbar (email virtualization PLEASEREMOVEME AT nachbar DOT biz)


Disclaimer: I'm not affiliated with OpenVZ - just a very satisfied user spreading the love ;)


Additional notes on this talk (external link)


OpenVZ is basically Solaris Zones, but open source, and works entirely on Linux. Install procedure on CentOS requires a new kernel (because they have lots of patches to virtualize certain things in the kernel), and some tools RPMs.