Virtualization Blog

Discussions and observations on virtualization.

Post-Creedence details to be presented at Xen Project User Summit

Last month I posted seeking feedback from you our community on what the post-Creedence world should look like. The response was impressive, and we've started incorporating what you want in a virtualization platform into our plans for the next release of XenServer; occurring after Creedence. While it's a bit early to divulge those details, I plan as part of my session on Creedence at the Xen Project User Summit to give you a roadmap for what to expect, what the code name will be for the project, and how you can help move the project forward. There will also be a few other surprises at the event for XenServer attendees, so if are able to be in New York City on September 15th please do try and join us. Not only will you be able to see what the new XenServer has to offer, but you'll see what the core hypervisor community is up to and potentially push them to help deliver features you feel valuable.     

Recent Comments
Russell Pavlicek
And don't forget that the leaders of the Xen Orchestra project will be presenting at Xen Project User Summit too. If you've ever ... Read More
Tuesday, 26 August 2014 20:06
Tobias Kreidl
I would like to see XenServer/XenDesktop embrace similar technology to the VMware Project Fargo, where a clone on demand of a live... Read More
Saturday, 30 August 2014 15:00
Sam McLeod
Hi, will the talks be uploaded online after for those who can't attend? Thanks,
Thursday, 11 September 2014 04:13
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Call for Participation for Xen User Summit

The Xen Project team is once again hosting a Xen Project User Summit, and this year they'd like to get some XAPI and XenServer related discussions going.  This is a perfect opportunity to showcase how you've used XenServer or XCP to solve real world problems, and provide valuable insight to others in the community on how to avoid any problems you've run into.  If you'd like to submit a proposal for a talk, or know of someone who would be perfect to cover cool XenServer/XCP content, then please do consider submitting something.

Important Details

When: September 15th, 2014

Where: New York City, Lighthouse Executive Conference Center

Where to submit topics: Linux Foundation Xen Project User Summit

Deadline: May 31st, 2014


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JK Benedict
In short: xsconsole, xapi/xe as an open source download, and additional security XSCONSOLE -- Personally, I have modified the cod... Read More
Saturday, 17 May 2014 22:07
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XenServer at the Xen Project Developer Summit

Last month Edinburgh was host to the latest Xen Project Developer Summit.  For those who attended, and for those who couldn't make it this time, the session recordings and presentations have just been posted.  The event saw content ranging from Xen on ARM and Xen in automotive infotainment, through to deeper discussions on fault tolerant system design and video display handling from a significant number of non-Citrix presenters.  Of course there were several XenServer related sessions, and I’m including the abstracts and links for them below.

“Unlimited” Event Channels

David Vrabel, Citrix

Event Channels are Xen's mechanism for paravirtualized interrupts. These were limited to only 4096 which then limits the number of guests that a host may support to around 300 to 500. This presentation will give a brief introduction to event channels, a detailed look at the new, innovative FIFO-based event channel ABI that increases the limit to over 100,000 as well as having several other useful features (e.g., multiple priorities). Some of the key performance measurements of the new ABI will be shown.

View presentation          View session recording

Test-as-a-Service and XenRT

Alex Brett, Citrix

In this presentation, Alex Brett will show how Citrix has constructed a Test-as-a-Service environment which is used by the wider XenServer engineering team, highlighting the benefits the approach provides, together with an introduction to the (recently open sourced) XenRT automation framework which powers it, and discuss how this could be applied within the Xen Project community.

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Increasing XenServer’s VM Density

Jonathan Davies, Citrix

As the number of CPU cores in server-class hardware increases, the demand on a virtualisation platform increases for greater VM density. Most commercial virtualisation platforms now support several hundred VMs per host. This talk will describe the scalability challenges that were overcome in Citrix XenServer 6.2 to enable support for up to 500 fully virtualised or 650 paravirtualised VMs per host. These include limits with event channels, blktap, xenstored and consoled. It will also discuss how dom0 CPU utilisation was reduced in order to make a large number of VMs responsive and thus usable, and will present benchmark measurements quantifying these improvements.

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Open Source Citrix Windows PV Drivers

Paul Durrant, Citrix

Citrix has recently spent several months making sure all the key parts of XenServer are open source. Part of this effort made the XenServer Windows Paravirtual (PV) drivers available in source form under a BSD 2 clause license on GitHub. Building these drivers outside of the internal Citrix XenServer build environment was quite hard and the resulting binaries would only run correctly in a XenServer host environment. I have recently spent many weeks modifying the drivers so that they should work on any recent upstream Xen host environment thus making it much easier for anyone outside of Citrix to build and deploy the drivers. I would therefore like to give a brief tour of all the drivers, their source, what each of them does, and how they all interact. I will also discuss plans for posting signed versions of these drivers onto Windows Update for general use by the community.

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xenserver-core: What it is, How it is Built and How to get Involved

Euan Harris, Citrix

XenServer is open source and freely available, but it is packaged as an appliance image which must be installed on dedicated hardware. xenserver-core repackages the core components of XenServer so they can easily be built and installed on a standard Linux distribution. Its main goals are: * to make it easy to download, modify and build XenServer components, or just learn how they work; * to help upstream distributions to include up-to-date XenServer packages; * to provide an environment for experimentation. This talk will explain the motivations behind xenserver-core and how it relates to the open-sourcing of XenServer. For developers, it will cover how to get the code, how to build it and how to contribute back to the project. For packagers, it will explain the project's development and release processes and what an upstream maintainer can expect from it.

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SecureServe: A Multi-level Secure Server Virtualization Platform on Xen

Jason Sonnek, Adventium Labs

Due to the rapid shift toward cloud computing, virtual desktop infrastructure (VDI) and thin client computing, many organizations in the government desire a high assurance, multi-level secure server virtualization platform that is low-cost, open and enterprise ready. In this presentation, Jason Sonnek will present SecureServe, a recently launched effort to develop such a platform by building on the open-source Citrix XenServer. The SecureServe project will draw upon research in a number of areas, including dom0 disaggregation, Xen Security Modules mandatory access controls and static/dynamic attestation. In this presentation, Jason will describe the project objectives and requirements, the project's relation to Citrix XenClient XT and XenServer Windsor, current development status and plans for moving forward.

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Delivering Continuous Deployment of Xen-API at Cloud Scale

John Garbutt, Rackspace

Currently xen-api is really only installed today as part of XenServer. It has traditional enterprise style releases, with controlled upgrades and hotfixes when required. When deploying OpenStack Rackspace, with the help of the OpenStack community, have adopted an approach where any check-in could be deployed, and the system upgraded, from any other checkin from that last release, or earlier in the current release. It would be interesting to see if xen-api could move towards a model. At a minimum having more regular check points where an upgrade would be possible. When running a cloud, a very small amount of control plane downtime is possible, but ideally there should be zero downtime for user's virtual machines. We should explore the ability to only upgrade Xen as a last resort, but still be able to update as much the control and data plane as possible, while keeping VMs alive.

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Multiple Device Emulators for HVM Guests

Paul Durrant, Citrix

Currently Xen only allows a single device emulator to be attached to each HVM guest in a system and, to date, this has been QEMU generally running as a process in the same domain as the toolstack, or in a stub domain. To enable the deployment of virtual GPUs to HVM guests in XenServer, patches were created to allow multiple device emulators to be attached to each HVM guest. QEMU continues to be used to emulate the majority of the devices, but a second process is spawned to handle the virtual GPU. This opens up the possibility of the GPU vendors supplying 'appliance' driver domains in future. I'd like to give an overview of the changes that we've made to Xen and QEMU to enable the use of multiple emulators, the potential benefits to driver domains, plus the knock on effect of emulator disaggregation on the 'unplug' protocol and what we could do about this.

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Xen and XenServer Storage Performance

Felipe Franciosi, Citrix

The development of low latency storage media such as modern Solid State Drives (SSD) brings new challenges to virtualisation platforms. For the first time, we are witnessing storage back ends which are so fast that the CPU time spent in processing data significantly impacts the delivered throughput. This is aggravated by CPU speeds remaining largely constant while storage solutions get faster by orders of magnitude. To meet user demands and fully exploit SSD performance under Xen, new technologies are necessary. This talk will discuss the Xen storage virtualisation data path when using various back ends (e.g. blkback, tapdisk, qemu). It will explain why it is hard to exploit SSD performance with current technologies and present measurement data for a variety of workloads. Finally, it will show how techniques such as persistent grants and indirect I/O can help to mitigate the problem.


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Recent comment in this post
Tobias Kreidl
Very interesting information, so thank you , Tim, for posting this. Above all, it is encouraging to see Citrix grabbing the stora... Read More
Monday, 30 December 2013 19:15
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About XenServer

XenServer is the leading open source virtualization platform, powered by the Xen Project hypervisor and the XAPI toolstack. It is used in the world's largest clouds and enterprises.
Technical support for XenServer is available from Citrix.