CopyCats in Virtualization

Step back in time with me a couple of years, Xen was starting it’s upmars and with Xen paravirtualization became popular , then came the other Virtualization vendors and the discussion about which technology was best discussed started.

Now we all know that VMWare and Xensource were discussing how to include hooks for Paravirtualization into the Linux kernel and eventually that also happened,however there wasn’t really any adoption , a couple of weeks ago VMWare announced it was going to drop support for paravirtualization. Aparrently VMWare’s Paravirtualization story wasn’t really a success.

The Xen folks pioneered with Paravirtualization and a dedicated hypervisor, yet somehow also got interrested in running the Xen engine within an already existing operating system by means of a kernel module. That way Xen can also be run on different existing platforms just as KVM and Virtualbox, one of the big reasons for KVM adoption exactly is the fact that one can turn an existing Linux machine into a virtual machine host by doing a simple modprobe

However the initial development focus for Hosted Xen was Windows and OS/X
not really a market wher Open Source Virtualization tools are going to make big
adoption steps fast

So you might wonder who is using this Hosted Xen anyhow , apparently not that many people. On the other side there’s VMWare’s ParaVirt similar story
And who’s using ParaVirt ? Aparently nobody …as there used to be a huge performance bug in it for over a year ..

So the lesson learned ? Stick with your own mainline technology .. no need to
copy the others ideas, seems like they won’t be a success anyhow ..

About the author

Kris Buytaert is a long time Linux and Open Source Consultant active in Belgium , Europe and the rest of the universe. He is currently working for Inuits Kris is the Co-Author of Virtualization with Xen ,used to be the maintainer of the openMosix HOWTO and author of different technical publications. He is frequently speaking at, or organizing different international conferences He spends most of his time working on Linux Clustering (both High Availability, Scalability and HPC), Virtualisation and Large Infrastructure Management projects hence trying to build infrastructures that can survive the 10th floor test, better known today as the cloud while actively promoting the devops idea ! His blog titled "Everything is a Freaking DNS Problem" can be found at


  1. Peter Novodvorsky says:

    VMWare uses paravirtualization and I hope is going to use it further. They are dropping some parts of VMI support, however I hope they will keep support for vmxnet and other paravirtual devices which appeared to be a huge success to vmware.

  2. @Peter:

    There is a difference between Paravirtualized drivers/devices and a fully Paravirtualized guest


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