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 Virtualization (Last updated: 23-01- 2008)
Virtual Server 2005 R2 VS Xen Server Enterprise


Queries the following Comparison is trying to Answer:


 Citrix Xen Server Enterprise VS Microsoft Virtual Server 2005 R2

 How does MS Virtual Server compare to Citrix Xen Server Enterprise ?

 Advantages & Disadvantages of Microsoft Virtual Server & Xen Ent

 What is better Citrix Xen Server Enterprise  or MS Virtual Server 2005? How?

 Independent Unbiased Comparison MS Virtual Server & Xen Server Enterprise


Citrix Xen Server Enterprise  VS MS Virtual Server 2005 R2 Introduction:


Ok, decided on riding the virtualization boat and confused on the right product for your company. You are in the correct place as here we list the comparisons of most of the virtualization solutions. On this page we will compare the Microsoft Virtual server 2005 R2 & Xen, but other comparisons are available and you can choose them from the menu on the left panel. Below is our unbiased comparison, but we still offer the some what biased comparisons which we has found at the links below


Microsoft Virtual Server 2005 R2 VS Xen Enterprise 4 (Microsoft Biased)

Microsoft Virtual Server 2005 R2 VS Xen Enterprise 4 (Xen Biased)


  Xen Microsoft

Just moved to server
ITComparison Comments Xen site is a bit easier to browse in regards of virtualization than Microsoft site due to the fact its their core business and they don't offer as much products to jam their site comparing to Microsoft.
Product Name Xen(Express, Server, and Enterprise) Virtual Server 2005 R2 (Standard and Enterprise)
ITComparison Comments Both are doing as good in regards of their naming convention.
Pricing range paid product Free - $2499 Free
ITComparison Comments



-: MS Virtual Server 2005 vs Citrix Xen Server Enterprise :-

This can really be misleading as for MS Virtual Server you still

have to pay for the host operating system, which you don't have

 to do if using Xen. In addition, in VMware Xen you can run more

virtual machines on the same specs machine as its running bare-metal

and waste less resource than Microsoft virtualization solution and in

many cases that it self will make up for the cost differences. Don't let

 the initial price fool you. Though Xen requires newer hardware as it needs Intel-VT or AMD-V to be supported which can play a role in the cost if you have an older hardware available.

Primary usage

Testing & Development  

Environment and some what production. 

Testing & Development  


ITComparison Comments

MS Virtual Server is mostly implemented in testing and development

environment in the enterprise, comparing to Xen who are pushing hard to compete with VMware on production environment.

Required Host OS (if any) Xen:bare metal

Windows Server 2003 SP1,

XP Pro SP2 (for testing  

purposes only)

ITComparison Comments

-: MS Virtual Server 2005 vs Citrix Xen Server Enterprise :-

Xen bare-metal installation (though it has a basic Linux Kernel in it) it still harden the security of its product and make it less affected of any operating system security risks and breaches unlike the Microsoft Virtual Server which unfortunately still affected by all the underlying OS (Windows 2003) bugs, viruses, and security breaches. In addition, not using underlying full fat OS make it more resource efficient.

Management tools  XenCenter Administrator Console

System Center Virtual Machine

Manager 2007

ITComparison Comments

Microsoft has just released their System Center Virtual

Machine Manager 2007. As well Xen has just crafted their newly developed XenCenter Administrator Console, which is more feature rich than the Microsoft one.

Support resources Medium Medium
ITComparison Comments

Microsoft might seems to have more support resources than Xen, but when it comes to virtualization both Microsoft & Xen are in the same boat and they are investing into that direction.

Supported Guest OS


o Windows Server 2003 Web, Standard, Enterprise, Datacenter SP2


o Windows Server 2003 Web, Standard, Enterprise, Datacenter SP0/ SP1/SP2/R2

o Windows XP SP2

o Windows 2000 SP4

- Red Hat Enterprise Linux (and derivatives (32-bit)): 3.5, 3.6, 3.7, 4.1, 4.2, 4.3, 4.4, 5

- Novell SUSE Linux Enterprise Server(32-bit): 9SP2, 9SP3, 10SP1

- Debian(32-bit): Sarge (3.1), Etch (4.0)

- Microsoft Windows Server 2003 Standard/Enterprise SP1/SP2/R2

- Windows XP Professional with SP2

-  Vista (Enterprise/Business/

 Ultimate) (non-production use)        

 - Microsoft Server 2008 Beta 3  

(non-production use only)    

- OS/2 4.5                              

- Red Hat Enterprise Linux 2.1 

(update 7) - 3.0 (update 8) - 4.0 

(update 4)                             

- Suse Linux Enterprise 9.0/9.3/10.0 /10.1/10.2            

- Solaris 10


ITComparison Comments

-: MS Virtual Server 2005 vs Citrix Xen Server Enterprise :-

Both are quite tide on the number of Operating Systems supported, but Xen has a more hardware requirements to run windows OS(Intel-VT or AMD-V is required to run windows on Xen). Xen has to enclose its hypervisor into Linux to perform well on it. Microsoft on the other hand does not require any modification to the Operating Systems to run on their Virtual Servers.


- Higher Performance

- More virtual Machines per hardware

- Slower Performance

- fewer Virtual Machines per  




The performance advantage of Xen is related directly with it being

running at near bare-metal and have a smaller foot print than Microsoft Virtual Server.

64-bit Support support the 64-bit version of Windows Server 2003 Web, Standard, Enterprise, Datacenter SP2 Does not support any 64-bit Operating Systems.
ITComparison Comments Its odd that Microsoft still does not support even their own 64-bit OS versions in their Virtual Server, where Xen support them.

Live Migration


High Availability


Dynamic Resources



Not Supported

Not Supported

Not Supported

Not Supported

Not Supported




-: MS Virtual Server 2005 vs Citrix Xen Server Enterprise :-

VMotion is a great features that VMware came up with and Xen achieved the similar by implementing XenMotion and Microsoft still does not offer any equivalence as XenMotion highly reduces the needs for hardware maintenance windows and downtime is a great missed feature in MS Virtual Server.
Special Hardware Requirement Require newer server which has Intel-VT or AMD-V Processor. Does not require any.



This is an advantage of Microsoft Virtual Server as you can run it on any PC or older server without requiring Processor.

Other Related Comparisons:


VMware ESX 4.0 vs Hyper-V R2

Xen Server Enterprise VS VMware Virtual Infrastructure 3

Microsoft Virtual Server 2005 R2 VS VMware Virtual Infrastructure 3

Microsoft Windows Hyper-V (WSV) VS VMware Virtual Infrastructure 3.5


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