back to article How Citrix dropped the ball on Xen ... according to Citrix

What's the difference between the Citrix Hypervisor and Xen? Well, one has quite a big crowd of upset current and former community members. One of the more interesting talks at the Open Source Summit was from Jonathan Headland, software development manager at Citrix, with the unusual title "How to Disengage the Open-Source …

  1. Will Godfrey Silver badge
    Thumb Up


    It's rare for any business to publicly admit it made a mistake, and to go into such detail is unheard of!

    1. Anonymous Coward
      Anonymous Coward

      Re: Impressive

      Agreed. It is very refreshing to see such candor about missteps and mistakes. I wish them good luck in the future as a result, rather than adding myself to the list of those fed up with their antics.

    2. druck Silver badge
      Thumb Up

      Re: Impressive

      I've worked with Jonathan, and he certainly says it as he sees it.

  2. Anonymous Coward
    Anonymous Coward

    Nice to see the admittal

    They are doing similar BS with Citrix Cloud. I am a 20 Citrix Virtual Apps and Desktops veteran, but I now need to get "experience" with Citrix Cloud. This usually means I run it a lab, with a mixture of purchased and evaluation licenses.

    You can spend $3000 on a 3 day course, which completely blows since that is no where near enough time to teach, much less absorb. I tried this method, learned a little, but no muscle memory gained.

    You can get a 7 day trial to play with yourself. Again, not enough time to learn or create muscle memory.

    I know this is a different product from the article, but I bring this up because of the statement "Understand and support the whole community: not just upstream, but downstream and other stakeholders".

    As I see it, your greatest Evangelists is your Certified Citrix Admin. Give them a helping hand here!

    1. TonyJ Silver badge

      Re: Nice to Thisee the admittal

      This where Citrix have let us down forever.

      Around 22 years ago I became CCEA #54 and full of enthusiasm for them.

      This, at a time when things like the MCSE gave you free software galore, I hoped I'd get in on the act.

      No. What I got, other than an ever-shittier certificate (seriously from the CCA which had the usual quality certificate feel, plus the expected hologram to one that looked like it'd been printed onto toilet paper using a broken 1st generation deskjet ink jet printer from HP) was access to a CCEA-only website.

      Which might have been ok except the only information on there was a list of exams you needed to pass to become a CCEA... ok then.

      It tempered my enthusiasm somewhat.

      Edit: This isn't limited to Citrix. Take MS as another poor example. They removed their technet subscriptions (years ago now) with the helpful advice: "Well most of our free trials run for 180 days". Cute. But what I wanted to do, was learn how to migrate from version x to version y, z or even aa, etc, because the client I am about to go to is using x and I don't have it installed.

      Evangelist to cynic in 3, 2, 1....

  3. Anonymous Coward
    Anonymous Coward

    Errm… no

    What actually happened was that XenServer was only supported on Windows (I think the management GUI is still Windows only)

    So…. RedHat bought KVM, went through the process of getting it mainlined…. And the rest was history.

    No one pays for hypervisor a these days, and all of them are “good enough”…

    1. Anonymous Coward
      Anonymous Coward

      Re: Errm… no

      No, XenServer was not "only supported on Windows" (XenServer wasn't/isn't a program that is installed in Windows, it's a bare metal type 1 hypervisor running a management VM which is based on CentOS), and aside from Windows did support Linux as well. Yes, the management tool was a Windows application, but that was the same with VMware ESXi back then (ESXi could be managed through either a standalone Windows application or through what later became vCenter installed on a Windows VM).

      XenServer also wasn't the most reliable or performant solution and often even worse than early Hyper-V.

      1. Anonymous Coward
        Anonymous Coward

        Re: Errm… no

        How do you even create a VM if you don’t have the management console?

        Also, it went through a Windows only guest for a little while.

        As you say, just because Linux appeared to work doesn’t mean it was reliable or actually supported.

  4. Anonymous Coward
    Anonymous Coward

    "We didn't mean to cause any harm. We wanted to be good citizens."

    The rumor was that Microsoft and Citrix decided to buy XenServer to prevent competition with HyperV, and to attack Vmware.

    1. captain veg Silver badge

      Re: "We didn't mean to cause any harm. We wanted to be good citizens."

      I can't cite where, but I remember reading a suggestion that HyperV was ripped off from Xen.

      Couldn't possibly be true.


      1. thames

        Re: "We didn't mean to cause any harm. We wanted to be good citizens."

        Microsoft HyperV is apparently a fork of Xen. However, Xen originated as a project at Cambridge University which was partially financed by Microsoft, so it's not as if they came along late in the game after Xen was already in the commercial market.

        Some Hyper-V source code from Microsoft later ended up merged back into Xen. I can recall seeing it and the comments and variable names made its origin pretty clear (the "HyperV" name was all through it). This had its 5 minutes of fame more than a decade ago.

        Cambridge's goal in the 1990s was to create what we would today call "cloud computing", and what we call Xen today was the hypervisor part of it.

        1. XenGelist

          Re: "We didn't mean to cause any harm. We wanted to be good citizens."

          Not true. M$ hired Novell/XenSource (KY and C. Griffin's team) to write specs for 'shim' and code 'enlightment' as part of NOVL/MSFT interop. - B2T: The campaign 'XenDesktop runs best on HyperV' killed XenServer business.

      2. Liam Proven (Written by Reg staff) Silver badge

        Re: "We didn't mean to cause any harm. We wanted to be good citizens."

        [Author here]

        Back in the very early years of this century, I interviewed the founder and "chief scientist" of Connectix. (He started the company then farmed off actually running it to someone else.)

        He co-developed VirtualPC. It was originally a Mac product, for PowerMacs running Classic MacOS. So it did whole-PC emulation; it had to, it wasn't running on a PC or on x86.

        Then, later, due to the success of VMware in its original desktop incarnation, Connectix ported VirtualPC to the PC.

        He told me with a big grin: "You'd be amazed how easy and efficient emulating x86 on x86 is. The architectures are a *really* close match."

        Microsoft bought Connectix:

        I've written about it on the Reg:

        On Linux, KVM works by using the combination of 2 features: the built-in hardware virtualisation of modern Intel and AMD chips, and the software virtualisation tools of the QEMU emulator.

        On Windows, Hyper-V works in exactly the same way, by using the built-in hardware virtualisation features, plus the emulation bits of VirtualPC.

        HyperV still uses virtual disk formats derived from VirtualPC ones today. No, there's not much left of the original product, because all the bits it needed are now part of the hardware or part of the OS.

        I know the history because I was there, using it and writing about it.

        So, no, I do not believe that MS stole anything from Xen, because it didn't need to steal anything. It had already bought the tools it needed.

  5. Nate Amsden

    Citrix didn't push Xen hard at all

    At least in my dealings with Citrix and those I knew of at the time(this was ~8+ years ago), if Citrix came across a happy vmware customer they did not get pushy to try to get the customer to replace vmware with their Xen. I admired them for that. At least the reps that did that anyway. They weren't going to push what was in their eyes(and mine!) a substandard product (to vmware anyway) on a customer and risk making problems just to close the sale. But if the customer was absolutely interested in cutting costs at the expense of quality then Citrix would happily entertain you with their Xen hypervisor offerings.

    My time as a Citrix customer is limited to the past 10 and a half years, 99% of that being Netscaler. Have never used Xen hypervisor, or any of their other products other than I had a small deployment of XenApp(?) for several years, it was a single server deployment, special license that they depreciated almost immediately after I bought it. It ran great for it's use case though (5 users max),just running a few various windows utility apps (such as the windows vSphere client remotely, and the older Java interface to Netscaler). I'd still have it now(despite being out of support for years), but had to retire it when I ditched my windows domains a few years ago, as far as I could tell XenApp would not function outside of a domain environment, so I gave up. Fortunately the number of apps that I wanted to use had dwindled a lot over the years.

    I am a happy customer overall, though the first several years spent a lot of time with support working through some Netscaler issues(mostly Access Gateway client related, and what is/was called Citrix Datastream, their SQL load balancing).

  6. Anonymous Coward
    Anonymous Coward

    Product managers can often do more harm than good, particularly if it's an invisible product and they aren't technical.

  7. Anonymous Coward
    Anonymous Coward

    Vmware started from an open project as well

    Back in the day there was this plexNN project (where NN is a number I forgot) that was working on a hypervisor.

    They got used by a start-up.

    Then vanished.

    That's why the vmware server ran on redhat.

  8. JacobZ


    As well as being honest, this is the kind of openness and frankness that the open source community need to see if they are ever to trust Citrix again. After all, nobody smart would trust Citrix with a future freemium model if they didn't believe it had learned lessons from Xen.

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