PeopleofSuperintelligence

Researcher

Keir Fraser

Also known as Keir A. Fraser

Keir Fraser is a systems engineer who helped create the Xen hypervisor, virtualization software that began as a Cambridge research project and became the basis of Citrix XenServer. His doctoral dissertation, submitted in 2003, covered lock-free data structures, and in 2003 he coauthored the paper "Xen and the Art of Virtualization"; in 2005 he coauthored a paper on live migration of virtual machines. He co-founded XenSource in 2005, which Citrix acquired in 2007 for US$500M, and he accepted a Linux New Media Award for Xen in 2010. From 2011 he was chief architect of the storage startup Coho Data, which closed in August 2017, and in 2016 he stepped down as a Xen committer.

Badges

Timeline

  1. 2003–2004

    A PhD on lock-freedom

    He submits his doctoral dissertation, Practical lock-freedom, to the University of Cambridge's King's College in September 2003. Cambridge publishes it as technical report UCAM-CL-TR-579 in February 2004, with practical abstractions and data structures for building large-scale lock-free systems.

  2. 2003

    The Xen hypervisor at Cambridge

    Xen begins as a Cambridge research project led by Ian Pratt and his PhD student Keir Fraser. In January 2003, he coauthors the technical report describing Xen, a hypervisor that lets several guest operating systems run on one machine. In October 2003, he coauthors "Xen and the Art of Virtualization" for the ACM Symposium on Operating Systems Principles.

  3. 2005

    Academic Fellow at Cambridge

    He joins the University of Cambridge as an EPSRC Academic Fellow in January 2005, after finishing his PhD. In 2005, he also coauthors "Live Migration of Virtual Machines", presented at the 2nd Symposium on Networked Systems Design and Implementation (NSDI 05).

  4. 2005–2007

    Co-founding XenSource

    In 2005, he co-founds XenSource with Ian Pratt and Steven Hand to provide a robust open source version of Xen. Citrix Systems acquires the company in 2007 for US$500M, and he leaves Cambridge in December 2007 to join XenSource. Xen goes on to form the basis of Citrix XenServer.

  5. 2010

    A Linux New Media Award

    In March 2010, he accepts the Best Open Source Solution for Cloud Computing award, won by Xen at the 10th annual Linux New Media Awards at CeBIT in Hannover.

  6. 2011–2017

    Chief architect at Coho Data

    In 2011, he helps found the storage startup Coho Data as its chief architect, with CEO Ramana Jonnala and CTO Andrew Warfield. The company raises US$65m in three funding rounds before it closes in August 2017.

  7. 2016

    Stepping down as Xen committer

    In 2016, the Xen Project announces that he and Tim Deegan have formally stepped down as committers on its hypervisor team.

Career

  1. 2011–2017Coho DataCo-founder, Chief Architect
  2. From 2005University of CambridgeAcademic Fellow
  3. From 2005XenSourceCo-founder

Education

  1. 2004University of CambridgePhD

From the biography.

  1. 11% of AI doctorate holders from 2010 to 2016 founded or led a company or lab by 10 years after graduationIncludes Keir Fraser. We estimate how often AI doctorate holders founded or led a company or lab by 10 years after graduation, how waiting times compare between founders and top jobs, and which universities trained the most.
  2. More people shaping AI studied at Massachusetts Institute of Technology than at any other institutionIncludes University of Cambridge. We estimate where the people shaping AI studied and where their careers led. Massachusetts Institute of Technology leads with 467 former students, including 291 recorded doctorates.
  3. The median h-index is 48 at universities and 14 at frontier AI labsIncludes University of Cambridge. The median h-index is 48 at universities and 14 at frontier AI labs. We compare publishing careers, recent citations, dual appointments and job moves across 2,420 university researchers and 308 frontier-lab researchers.
  4. Companies supply the most prior-work hires at 7 of the 9 frontier AI labsIncludes University of Cambridge. Our estimates of the organizations where 550 people worked directly before joining 9 frontier AI labs across 620 career transitions, comparing the main feeder organizations per lab.

Colleagues

People with dated positions at the same organization in the same years.

Sources and credits

Photo: We have no published photo of Keir Fraser yet. Send us a free-licensed photo.

  1. Department of Computer Science and Technology – Technical reports: UCAM-CL-TR-579 cl.cam.ac.uk. Checked 21 October 2026.
  2. Xen - Wikipedia en.wikipedia.org. Checked 21 October 2026.
  3. Department of Computer Science and Technology – Technical reports: UCAM-CL-TR-553 cl.cam.ac.uk. Checked 21 October 2026.
  4. Xen - REF 2014 impact case study, University of Cambridge impact.ref.ac.uk. Checked 21 October 2026.
  5. Live Migration of Virtual Machines | USENIX usenix.org. Checked 21 October 2026.
  6. Keir Fraser Makes Rare Appearance to Accept Xen Award xenproject.org. Checked 21 October 2026.
  7. The down low on why Coho Data is a no-go theregister.com. Checked 21 October 2026.
  8. Coho Data falls victim to 'cutthroat' data storage market | TechTarget techtarget.com. Checked 21 October 2026.
  9. Please Welcome new Members of the Xen Project Hypervisor Leadership Team xenproject.org. Checked 21 October 2026.