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Creedence launches as XenServer 6.5

Today the entire XenServer team is very proud to announce that Creedence has officially been released as XenServer 6.5. It is available for download from, and is recommended for all new XenServer installs. We're so confident in what has been produced that I'm encouraging all XenServer 6.2 users to upgrade at their earliest convenience. So what have we actually accomplished?

The headline features

Every product release I've ever done, and there have been quite a large number over the years, has had some headline features; but Creedence is a bit different. Creedence wasn't about new features, and Creedence wasn't about chasing some perceived competitor. Creedence very much was about getting the details right for XenServer. It was about creating a very solid platform upon which anyone can comfortably, and successfully, build a virtualized data center regardless of workload. Creedence consisted of a lot of mundane improvements whose combination made for one seriously incredible outcome; Creedence restored the credibility of XenServer within the entire virtualization community. We even made up some t-shirts that the cool kids want ;)

So let's look at some of those mundane improvements, and see just how significant they really are.

  • 64 bit dom0 freed us from the limitations of dreaded Linux low memory, but also allows us to use modern drivers and work better with modern servers. From personal experience, when I took alpha.2 and installed it on some of my test Dell servers, it automatically detected my hardware RAID without my having to jump through any driver disk hoops. That was huge for me.
  • The move to a 3.10 kernel from meant that we were out of the business of having a completely custom kernel and corresponding patch queue. Upstream is goodness.
  • The move to the Xen Project hypervisor 4.4 meant that we're now consuming the most stable version of the core hypervisor available to us.
  • We've updated to an ovs 2.10 virtual switch giving us improved network stability when the virtual switch is under serious pressure. While we introduced the ovs way back in December of 2010, there remained cases where the legacy Linux bridge worked best. With Creedence, those situations should be very few and far between
  • A thread per vif model was introduced to better ensure network hogs didn't impact adjacent VM performance
  • Network datapath optimizations allow us to drive line rate for 10Gbps NICs, and we're doing pretty well with 40Gbps NICs.
  • Storage was improved through an update to tapdisk3, and the team did a fantastic job of engaging with the community to provide performance details. Overall we've seen very significant improvements in aggregate disk throughput, and when you're virtualizing it's the aggregate which matters more than the single VM case.

What this really means for you is that XenServer 6.5 has a ton more headroom than 6.2 ever did. If you happen to be on even older versions, you'll likely find that while 6.5 looks familiar, it's not quite like any other XenServer you've seen. As has been said multiple times in blog comments, and by multiple people, this is going to be the best release ever. In his blog, Steve Wilson has a few performance graphs to share for those doubters. 

The future

While today we've officially released Creedence, much more work remains. There is a backlog of items we really want to accomplish, and you've already provided a pretty long list of features for us to figure out how to make. The next project will be unveiled very soon, and you can count on having access to it early and being able to provide feedback just as the thousands of pre-release participants did for Creedence. Creedence is very much a success of the community as it is an engineering success.

Thank you to everyone involved. The hard work doesn't go unnoticed.     

Tim Mackey is a community manager and evangelist for XenServer within the Citrix Open Source Business Office and is focused on server virtualization and cloud orchestration technical competencies. He joined Citrix through the Reflectent acquisition in 2006, and served as architect and developer for Citrix EdgeSight; an end user experience performance monitoring solution. In 2007, Mr. Mackey became technical product manager for the EdgeSight product line and then in 2009 product manager for the XenServer self-service virtualization components. Since that time, he has held various roles within the XenServer team, and speaks regularly on topics related to the design of large scale virtual environments.


  • Guest
    james Tuesday, 13 January 2015

    Yay ! congratulations for the entire XS team at Citrix and the community
    wishing XS team continued success in making XS the Linux of Server Virtualization !

    Reply Cancel
  • Fabian
    Fabian Tuesday, 13 January 2015

    Finally! Now hope that it's as stable in production as it was during the testing phase... Fingers crossed here.

    BTW: There's a typo on the download page: "Supplimental" instead of "Supplemental"

    Reply Cancel
  • Tim Mackey
    Tim Mackey Tuesday, 13 January 2015

    @James, thanks for the kinds words

    @Fabian, I would expect things to be just as stable, and thanks for the catch.

  • Tobias Kreidl
    Tobias Kreidl Tuesday, 13 January 2015

    Did DVSC ever get bundled in with the free or at least other versions?

  • Tim Mackey
    Tim Mackey Tuesday, 13 January 2015


    DVSC is part of the commercial entitlements. Download DVSC from, but will work with XenServer 6.5 host deployed using installer from either or; assuming you have commercial license in place.

  • Andrew Halley
    Andrew Halley Monday, 19 January 2015

    Apologies for the confusion - DVSC is part of 6.2 and is part of 6.5. Using it does NOT in require a license - either in 6.2 or in 6.5. An updated licensing FAQ containing entitlements has been posted. Please reference, and if there are issues, please do submit feedback on the article.

  • Tobias Kreidl
    Tobias Kreidl Monday, 19 January 2015

    CTX141511 still does not state specifically what the requirements there are, if any, for licensing in order to use DVSC. It is not mentioned anywhere within the document. I have consequently submitted a report on it via the feedback mechanism.

  • Andrew Halley
    Andrew Halley Monday, 19 January 2015

    Thanks Tobias. Will take it on board. The idea is that if a feature is not explicity stated as being licensed it isn't. However - given the discussion - that's a decision we'll certainly revisit!

    Reply Cancel
  • JK Benedict
    JK Benedict Tuesday, 13 January 2015

    I applaud you (Tim) and the rest of the entire team + community for this release!

    While things stabilize post-holidays, I hope to see some Vendors with the "next generation" (ie, only 64-bit OS support) make it to the HCL.

    --jkbs | @xenfomation

  • Andrew Halley
    Andrew Halley Wednesday, 14 January 2015

    Am happy to say that we are starting the 6.5 HCL with a record number of listings. As a result of a lot of hard work from many teams we have published an initial HCL list for XenServer 6.5 that contains a record 313 listings! (servers, arrays and add-in cards we've have certified by either our partners, or XenRT internally).

  • Tim Mackey
    Tim Mackey Tuesday, 13 January 2015


    I looked this morning and the HCL was a bit light. Based on prior releases, I figure about a month for the backlog of stuff to show up.

  • Tobias Kreidl
    Tobias Kreidl Tuesday, 13 January 2015

    The licensing model has recrudesced. It is not immediately clear what can or cannot run as part of the "free" license. For XenDesktop Enterprise users, it is extremely disappointing to not be able to gain access to the in-memory read-cache feature.

    Aside from these licensing limitations, it is a great edition and all involved in the technical aspects of its being brought to fruition are to be heartily congratulated.

  • Guest
    Thomas Poppelgaard Tuesday, 13 January 2015

    Tobias read the summary I have made with XenServer there is also a feature chart


    Reply Cancel
  • Willem Boterenbrood
    Willem Boterenbrood Wednesday, 14 January 2015

    Thanks! For some reason Citrix has not provided us with a clear table that lists the differences between the additions, but this is really usefull. It would be great if you could add XenServer 6.2 free to the table as many people are running that version.

  • Tobias Kreidl
    Tobias Kreidl Tuesday, 13 January 2015

    Very nice, Thomas! Thanks much for providing that chart. Please be sure to add DVSC (supported all but the free edition, according to what Tim stated above). Thanks much!

  • John
    John Wednesday, 14 January 2015

    Congratulations to the whole team. We'll be rolling the 6.5 SDK into products immediately and start the push to get our clients on to 6.5

    Great work - here's to the future of XenServer.

  • Mohd Akhbar
    Mohd Akhbar Wednesday, 14 January 2015

    Good job XS Team. Look forward to try it out.

  • Mohd Akhbar
    Mohd Akhbar Wednesday, 14 January 2015

    Great job XS Team. We have few servers running 6.2 serving various services, and we look forward to upgrade to 6.5

    Thank you.

  • Willem Boterenbrood
    Willem Boterenbrood Wednesday, 14 January 2015

    Congrats to the XenServer Team, happy to see the best XenServer ever released.

    There are however some things that make me less happy which I want to share with you:
    While Creedence is a major step forward a lot of the new improvements are things that vSphere and Hyper-V had for some time, and most of the improvements are under the hood and not necessarily something new but mostly something improved. I guess this is why Creedence became XenServer 6.5 and not 7.0. Now these improvements in Creedence are needed to get to the next step so its good everything happens in the correct order but compared to vSphere and Hyper-V XenServer is missing many usefull things like Thin Provisioning on SAN, Changed Block Tracking and more, while not providing many strong advantages (I see mainly XenDesktop vGPU) I really hope the next release will bring many of those wanted features to XenServer. Unfortunately Citrix has decided on releasing 5 versions which I think is too much, they wanted to make as much money as possible but now they have locked out most users of the only big new functionality 6.5 has over 6.2 which is In memory Read-Caching. DVSC did work in 6.2 free and this is now also payed only which is also not good, i don't know about intellichache and vGPU but I was under the impression that those also worked in 6.2 free as 6.2 was open source and the only difference was support. I can understand that things like workload balancing with 3rd party licensing are not open source and free but to me it looks like 6.5 is much less open than 6.2. Now I understand there needs to be money to create the software and compared to vSphere pricing is good but most companies can run Hyper-V HA free with more functionality that a free XenServer will give, so that is lost potential I think.

  • Andrew Halley
    Andrew Halley Thursday, 15 January 2015

    Hi there. Fully take your comments on board. There is active development on thin provisioning where we have been investigating various design and architecture projects. I expect you will start to see activities in that direction on the trunk nightly builds shortly as we put together code for future versions. In terms of change block tracking then there are some recent developments which are available here :

    The new APIs allow you to
    - export and import disks in .vhd format (previously we only supported raw). This means the files are sparse.
    - export and import only the blocks which have changed between two snapshots. This allows you to avoid re-copying the same data again and again.
    These are available now. We would be happy to know what you think - and best way to do this is to join the xs-devel mailing list. Details on how to do this are available hereon
    Intellichache is available in all versions, and does not require a license.

    Reply Cancel

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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.
Commercial support for XenServer is available from Citrix.