Monthly Archives: July 2008

Xen Training Day at USENIX Annual Technical Conference

The day before Xen Summit in Boston a few weeks back, hosted a Xen Training Day for attendees of the USENIX conference. 37 people attended a day long session about Xen which covered the basics of the Xen hypervisor as well as more complex subjects such as file systems, live relocation, etc. The session was taped and available along with the presentation slides (see links below). Thanks to Todd Deshane and Patrick Wilbur from Clarkson University for putting together all the information and demos for this training.

Session Description:

Session Slides (Open Office Format):

Audio (MP3):

Audio (OGG):

General Xen Information HTML Page for Attendees:

Finally, the USENIX folks have invited to repeat this training at LISA ’08 in a few months in San Diego. will continue to have training for Xen at various events to further promote this great open source solution.

Help finding a web catalog search tool

Xen Community:

I am looking to build an online search tool that allows Xen customers/prospects to search for solutions using/based on Xen. The search tool would take the prospects to a web page with content maintained by the solution provider – open source or proprietary. I believe adding this feature to would be a great tool for all the businesses based on Xen.

So, anyone know of anything available that I can use? I spoke with a company last year in Minnesota  that offers something usable for about $20,000 so I am hoping to find something a bit more affordable. Any advice would be greatly appreciated.

Ian Pratt at USENIX Annual Tech Conference 2008

Ian Pratt spoke at the USENIX Annual Technical Conference a few weeks back in Boston. Here are the slides from that presentation.

Talk overview:

This is a talk in three parts. I’ll give a summary of the Xen story so far, looking at how Xen made the transition from research project to enterprise software and the many challenges along the way. Next, I’ll look at why virtualization is such a hot topic in IT and the failings of common operating systems that have led to this. I’ll then look at how Xen has evolved since the 2004 SOSP paper, seeing how paravirtualization and software/hardware co-design have helped reduce the overhead of virtualization.

Xen Summit Highlights – Kemari – High Availability 2.0

Yoshi Tamura from the NTT Cyber Space Laboratories in Japan gave a very interesting presentation on Kemari. Kemari is a new approach to cluster systems that synchronize VMs for fault tolerance without modifying neither hardware nor applications.

Since virtualization puts an abstract layer between hardware and operating system, it also offers the possibility to migrate virtual machines between physical hosts – but that’s no magic these days. When it comes to high availability and virtual machines today, the approaches mostly consist of using the image-file on a shared data-storage and having multiple copies of configuration files on the potential physical hosts. If one of the hosts breaks, another takes over and automatically fires up the configuration file to boot the virtual machine.

Kemari goes a step further. The word Kemari comes from a traditional Japanese football game where you are supposed not to drop the ball. In the context of virtualization it means: Don’t drop the virtual machine!

But how do you make sure the virtual machine is continuing to run with no noticeable downtime? The most obvious technology for this is synchronization. One could pause the VM, copy a snapshot to a secondary server and unpause the VM on the primary server once the transfer has been ended successfully. The snapshot for this moment is then available to the secondary node. But what about storage, network and console events that occur in between the snapshots of the VM?


There are two ways to realize this. The first one is the so called lock-step approach which logs the external events on the primary VM and transfers them to the secondary VM where they need to be replayed. The disadvantage of this is the complicated implementation if you are trying to synchronize two VMs between different processor families – there might be events that cannot be replayed easily. The second approach uses continuous checkpoints (REMUS project at UBC).  Here the outputs on the primary VM are buffered and delayed until the secondary VM is being updated.

Kemari is using a hybrid approach. It traps events sent by the frontend driver of the primary VM through the Xen event channel and sends them to the secondary VM. By snapshoting the VM before the event is sent out to hardware, there are no inconsistencies in case the secondary VM has to take over.

Yoshi also brought a demonstration video with him. Here he showed how a xclock kept running although the primary physical server was shutdown through the HP iLO board. There was only a little pause (<1 sec) but the VNC session and the clock kept running on the secondary server. His presentation can be found here and an abstract of the Kemari architecture is located here.

The ambitious work and open discussion of these completely new and promising approaches (both Kemari and Remus) will make Xen and virtualization in general more and more popular. Once this is included in the core Xen hypervisor, high availability comes to the masses: high availability 2.0.

Xen Summit Tokyo (Asia) Program Committee Request

Xen Summit Tokyo (Asia) sponsored by Fujitsu is fast approaching and I am calling for Program Committee volunteers interested in reviewing all submitted topics and creating the event agenda. I hope to have at least 7 people on the Program Committee for this event so if you are interested, please send me your contract information by July 15, 2008. As the event is in Tokyo, I am looking for volunteers who speak Japanese as many of the topic submissions will be in Japanese; however, speaking Japanese is not a requirement to participate on the Program Committee. If you have any questions or would like to volunteer to be on the Program Committee, please email I look forward to working with the Xen Community in creating an educational event for the Asian community.


Xen Summit Tokyo (ASIA)、Xenサミット東京開催に向けて、第一歩としてプログラム委員