Microsoft and Citrix clarify XenSource / Hyper-V interaction. Both companies win.

Let's continue stepping through Tuesday's many virtualization announcements from Microsoft. Today we'll look at an announcement about how Microsoft and Citrix are going to work together even tighter in the virtualization space.

Let's continue stepping through Tuesday's many virtualization announcements from Microsoft. Today we'll look at an announcement about how Microsoft and Citrix are going to work together even tighter in the virtualization space. As we re-capped yesterday, Microsoft and Citrix announced months ago that Hyper-V and Xen would share the same virtual disk formats and that tools from Citrix (XenSource) would be able to manage both Hyper-V and Xen virtual machines, so Tuesday's announcement was really more of an extension of previous announcements.

From the press release:

Citrix is developing a software tool that will allow customers to easily transfer virtual machines between Citrix XenServer and Windows Server 2008 Hyper-V to help ensure greater interoperability for customers. A test version of the tool will be available in the second quarter, and a final version will be available with the release of Hyper-V.

Remember that Hyper-V is scheduled to be released six months after Windows Server 2008, so that puts it somewhere in the late-August 08 timeframe.

I don't actually 100% understand what this tool will do, because I thought it was already announced that these VM formats would be the same? Either way, it's easy to understand what this tool does, and it's cool that it will exist.

There was another part of the press release that I found more confusing:

Microsoft offers infrastructure virtualization software ... along with a comprehensive management platform, such as Microsoft System Center, to manage both virtual and physical infrastructure and applications. Microsoft delivers a simple, integrated management solution to manage across customers’ infrastructure: from the physical to the virtual; from the hardware to the application and services.

The phrases Microsoft used--"comprehensive management platform," "integrated management solution."--sound to me like Microsoft is positioning themselves that they can offer all you need for your virtual environment. Where does this leave Citrix?

If you read back through the announcements of the past several months, the "deal" was that Microsoft would provide Hyper-V, and Citrix would provide the management of Hyper-V via XenSource and Provisioning Server (Ardence). But how does System Center fit into this?

I posed this question to both the Citrix and Microsoft folks I talked to on the phone. They positioned it that Citrix is providing "capabilities," not "management tools" per se. These "capabilities" will be things like dynamic virtualization services, on-demand storage, provisioning of disk images, virtual machine streaming, interoperability between Hyper-V and Xen, etc.

So Citrix will "manage" these low-level capabilities, and then Microsoft (via System Center) will "manage the managers." What a great deal for Microsoft! They can be the manager without having to do the hard stuff. But what a great deal for Citrix! Without them, Microsoft's "comprehensive management platform" isn't quite so comprehensive.

Join the conversation


Send me notifications when other members comment.

Please create a username to comment.

I want to buy a complete solution from one vendor source.

Is Citrix dependent on MS or is MS dependent on Citrix with XEN? 


The only capabilities I see Citrix bringing to the Microsoft virtualization platform are Citrix Provisioning Server (Ardence) and XenDesktop. Other than that, the Microsoft offering seems pretty complete (once it is actually released).

Regarding the migration tool, it seems to me that Citrix has effectively agreed to be the “stepping stone” for Microsoft virtualization strategy: XenServer is the virtualization platform that you can use right now, and then upgrade to Hyper-V once it’s released. In fact, I wouldn’t be surprised if XenServer quietly disappears several months after Hyper-V is released, at least from the Windows platform.

If this will indeed be the case then Citrix will have spent $500M as a favor to Microsoft and for a bit of PR.


Things are not as complicated as they seem. If you buy a computer from HP you will also get it with a built-in hard drive that was not made by HP. Hyper-V and Xen define virtual machines - translate as computers with CPU, network adapters, main memory and hard disk controller, but NOT including the hard disk! The hypervisor is the thin layer between the physical hardware and all other software running on it, allowing a logical partitioning of the physical resources. This means that the hypervisor simply assignes a portion of the physical CPUs (or memory) to any virtual machine created through the hypervisor. Hyper-V and Xen follow pretty similar technical paths in doing that, but there are still differences -- one is based on Windows and the other on Linux. You may compare this to different UNIX flavors, such as Sun Solaris and HP-UX. Both are UNIX, but may not be able to run each others apps or management toos.

Microsoft and Xen/XenSource agreed that they want to use the same virtual hard disk format. It's like HP, Dell and IBM servers can use the same SATA disks, because they come with a standardized interface. This was step number one of the Microsoft/Xen agreement: standardize the virtual HD format (VHD). This has got nothing to do with the formats of virtual machines that can use the VHDs. HP servers also tend to have different main boards as Dell servers.

If we look at the virtual machines created by Hyper-V and Xen, they are NOT compatible today -- even if they can use the same hard disks. You may convert one type of virtual machine into another, but they are not directly exchangeable. And Hyper-V needs specific drivers for non-Windows OS's running in its virtual machines in order to talk to the Hyper-V VMBus which connects virtual machines with physical devices. The Hyper-V Beta only ships with VMBus drivers for Windows XP, Windows Server 2003, Windows Vista and Windows Server 2008 -- big surprise, isn't it? Now, looking at Linux/UNIX and drivers, this is something that Xen is really good at. So, Citrix/XenSource can help Microsoft to integrate non-Windows platforms into Hyper-V. This is what customers want if they compare Hyper-V with VMware. Now, after taking all this into account, the new MX/Citrix agreement is easy to understand.

So far we only looked at one server used for virtualization. But as we all know the real fun starts when you have more than one physical box running many VMs. Microsoft has System Center Virtual Machine Manager, Citrix also has management tools. Now both make sure that Citrix can manage Hyper-V and Microsoft can manage Xen -- and both also want to manage VMware ESX ;-) So there is even more room for co-opetition and announcements.

Not to forget the desktop brokers which help user to find their desktops/apps and help admins to manage both desktops and users. (Yes, I know that some desktop brokers can do even more) Microsoft has a broker solution integrated into System Center, Citrix has XenDesktop, Quest/Provision has VAS, VMware has... well, I could go on for a while with some name dropping. The most important fact is that generally speaking desktop brokers are pretty much independent of the hypervisor hosting the desktop OSes. So sure XenDesktop will support the most important hypervisors, which are provided by VMware, Citrix/Xen and Microsoft.

Now, to make a very long story short: We are talking about different layers of a complete technology stack, and both Microsoft and Citrix happen to own products that belong to one or the other layer. On a higher layer you always want to support all products on lower layers in order to generate more business. Hypervisors are the lowest layer, they are to become a commodity and vendors will give them away for (almost) free. It's a bit like the cell phone market. You can buy the hardware for $1 if you sign a mobile phone contract


For pure server virtualization situations, XenServer will be ahead of Hyper-V for some time.  For example, live migration of VM's across physical server is something many customers want.  XenServer has had this since mid 2007, and Hyper-V won't have this until 2009 (at the earliest).  This gives Citrix about 2 year lead on Microsoft for a key feature customers want.  XenServer will add other important features prior to Hyper-V shipping, like automatic failover/high availbility.

Citrix simply needs to stay ahead of Microsoft--just like with ICA and RDP which they've done well for over 10 years.  As soon as Citrix doesn't have a lead over Microsoft in one particular area, they'll just leverage what Microsoft has and find other areas to add on top.  With open source technology as the basis for XenServer, I think Citrix will do just fine keeping a healthy lead over Microsoft.  Requiring Windows Server 2008 in the parent partition of Hyper-V really slows Microsoft down from a development and market acceptance standpoint.  Keep in mind that they are still at least 6 months from shipping v1.0.

What both Microsoft and Citrix really want to see in 5-10 years is that Hyper-V is the #1 hypervisor and XenServer is #2.  Broad adoption of server virtualization benefits sales of Windows Server because it reduces the hardware "tax" involved, so Microsoft doesn't care if there is a healthy #2 vendor in this space (as long as it is a company the trust and have some influence over like Citrix).  VMware's possible error was trying to take on Microsoft directly and become an "operating system" vendor.   The announcements this week are one step along the way towards turning VMware into this decade's Novell.


over 24 months. So only higher-layer products or services are used to make money. And MS and Citrix obviously decided to join forces to leave a growing footprint in this market, simple as that. If they are lucky it's of mutual benefit for both.

Final remark: I don' t see ANY vendor that can deliver the ultimate and complete solution alone. Citrix seems to have invested US$500M to eriously belong to the top 5 vendors in this market



After playing around with Hyper-V intensively for some time now I have to agree with the previous comment posted by Guest ;-) Hyper-V is really good, taking into account that it is Microsoft's initial step to develop a real hypervisor and that it is a beta version. I was not able to crash it so far!  However, important features such as live migration are missing, even if Microsoft had it in a very early pre-beta version. I also guess that MS and Citrix are joining forces against VMware.



> XenServer will be ahead of Hyper-V for some time

This is certainly true given that Hyper-V doesn't exist yet as a product. But then ESX is ahead of XenServer, it will likely stay that way given its existing lead and VMware's greater resources.

> Citrix simply needs to stay ahead of Microsoft--just like with ICA and RDP which they've done well for over 10 years

This comparison is totally bogus. CPS and Microsoft TS do not compete. If Microsoft had decided to compete with Citrix for SBC it would have wiped Citrix out long ago. Hyper-V and XenServer will definitely compete once Hyper-V is released. Microsoft will put many more resources into Hyper-V's development than Citrix can ever put into XenServer. Since Microsoft is shooting for VMware I bet they'll bypass XenServer fairly quickly.

> What both Microsoft and Citrix really want to see in 5-10 years is that Hyper-V is the #1 hypervisor and XenServer is #2

Microsoft certainly wants do be #1, but I don't think their really give a damn who is #2.

> turning VMware into this decade's Novell

Novell lost because it fumbled badly. I haven't seen VMware fumble yet, quit the contrary. Microsoft may win but it will be quit a battle.


> Citrix seems to have invested US$500M to seriously belong to the top 5 vendors in this market

If Citrix ends up being number 4 or 5 I hardly see it generating enough revenue to justify spending $500M.


Absolutely true. This brings us back to the question why Citrix spent so much money for XenSource. Will they be able to get their investment back? But what if Microsoft pays Citrix good money to do some integration work and develop extensions for them behind the scenes? What if Microsoft "sublicenses" some of Citrix's IP just to be faster with Hyper-V? Some virus scan engine or search engine vendors make a good living with such a model.

But I admit, I'm just guessing. And I'm still having a hard time to understand the XenSource acquisition, or better, I still wonder what the real reasons for the acquisition were. Maybe Citrix' intention is to be the future #1 in the virtualization management market. Maybe they think that they can become the same in the virtualization market what HP OpenView, CA Unicenter or IBM Tivoli are in the system management market even if there was Microsoft SMS and MOM. If you don't even try to become a market leader you will never be one.



> What if Microsoft "sublicenses" some of Citrix's IP just to be faster with Hyper-V?

I recall reading somewhere that XenSource engineers helped Microsoft support Linux VMs. However integrating Xen IP into Hyper-V can be very problematic because Xen is GPL - see this very amusing post:

What if it's not about virtualizing servers, but desktops?  Think about it.  If DDI/VDI takes off, which I believe it will, the amount of desktops that will get virtualized will far out number servers.  Why would a company pay for ESX (rich feature set) to host desktops when you can do for a third of the cost on XenServer (simple feature set)?  They're desktops, not production servers that can't have any downtime.  Take it a step further and look at XenDeskop and you have a much lower TCO then if you did the same solution with VMWare VDI.  It's the only thing that makes sense and I'm betting this was the driver behind the $500M gamble.  If you're Microsoft, who would you rather have hosting your desktop software, VMWare or Citrix?

I attended a Citrix/Microsoft virtualization seminar that sounds like it will be a series in Seattle last Friday in one of Microsoft's offices.  It was standing room only with customers.  Peter Meister, group virtualization product manager from Microsoft, was the first presenter and talked about all the reasons why Microsoft was working with Citrix.  Simon Crosby, CTO of Xen/Citrix, spoke next and also discussed how Microsoft and Citrix would be taking on VMware.  His presentation was articulated very well and drew lots of questions.

Discussion around improvement gains of Presentation Server on XenServer vs. VMware ESX were discussed, plus, the organizations moving together on the VHD format and winning the virtual appliance war.

Overall, it was an excellent seminar and if it does come to your city, I would recommend it.


I have some experience on Xen, Vmware and Hyper-V. As far as i am concerned VMware has the most mature product of the moment.

But in the long run, this doesn't seem to matter.  

As an owner of 2 Xensource Xenenterprise 4 licenses, I'm about to install Windows Server 2008 tomorrow and play around with hyper-V in it's current beta format. While Xensource is excellent, Microsoft brings greater hardware compatability to the table, along with a more stable upgrade path into the future. If Microsoft allows you to run a Hyper-V system as a Core installation, then I'm questioning how much difference there will be between the performance of Xensource and Hyper-V. Also, microsoft's implimentation finally brings virtualization into the mainstream, where all products will benefit due to higher visibility in the marketplace.


It seems MS & Citrix are doing all they can to take VMware down. Will that scary dream become a reality?

Will MS keep their virtualization license to be free if VMware disappear?

To compare how these products are coming across we have posted a comparison between vmware VI3 & MS Hyper-V and we are using people comments at our VMware VI3 vs MS hyper-V forum to enhance it daily. We are hoping to keep up the most comprehensive comparison of the two products during this heated period. This will only possible with your help.


Thanks for your help,


We are heavy users of Citrix and VMware. At this time, I can see no advantage to Xen or Hyper-V. Why would someone not go with the more mature VMware product. Unless you are starting from scratch and want a single venor solution, I dont know why you would use Xen. As for Hyper-V, it will be like most MS add-ns and not be as fully functional as a third party sollution such as VMware or Xen.