Microsoft Virtual Server 2003 vs Vmware Server

Both Microsoft Virtual Server 2003 and Vmware Server are free virtual server hosts offering very similar features.

I have recently had the (mis)fortune of attempting to configure one of my personal servers as a Virtual Machine host in an attempt to consolidate all my servers and reduce my IT spend.

I currently have (separate) servers that fulfill the following roles:

  • Mail (Microsoft Exchange) Server
  • Web Server
  • Inbound/Outbound Mail Exchange

Whilst having these applications on separate physical machines increases redundancy, it creates a rather large monthly IT spend.

What I intend to do is to convert my Mail Server (Running Windows 2003) into a Virtual Machine host and then migrate all roles onto separate Virtual Machines. This also includes migrating the Exchange Server from the Host onto a Virtual Machine so as to minimize downtime.

My initial thought was to run Vmware as the Virtual Host platform, however this had some rather significant drawbacks:

  • Creating a new Virtual Machine disk locked the server up for 10 to 15 minutes.
  • The Linux installer would hang if any other Virtual Machine was running at the time of install.
  • Virtual Machine Guests were noticeably latent.
  • The Virtual Console requires a client to be installed.

In an attempt to resolve these problems, I tried Microsoft Virtual Server 2003.

The Virtual Server 2003 installer was faster, and Virtual Machines significantly more responsive. Creating a new Virtual Machine takes a matter of seconds with no noticeable adverse effects on the Virtual Machine Host.

Microsoft Virtual Server 2003 also comes with a rather nice web interface where you have full console access.

I admit that the latency problems may be partially caused by the fact that the Host has not yet had a RAM upgrade! It is currently running with 1GB DDRII instead of the 3GB it will have before being commissioned properly.

It appears that Microsoft win this one! Their Virtual Server platform appears to be rather awesome.

It has been suggested that I should use xen instead, however the constraint of running on a Windows 2003 Server Host Operating System has resulted in this being impossible.

4 Responses to “Microsoft Virtual Server 2003 vs Vmware Server”

  1. Jo-Erlend Schinstad Says:

    There is a checkbox in VMWare Server Console that asks whether you’d like to “Allocate all disk space now”. If you uncheck that, creation of a virtual machine is instantaneous, since a virtual machine really is only a very small text-file (~30 lines). Using sparse disk images, like MS Virtual Server obviously did — since no Windows application will be able to copy a many-gigabyte file in seconds — will get you somewhat lower disk I/O. I feel no lag on vmware server 1.0.4 at all, when I’ve installed vmware tools on the guest. I have no problems watching a movie in full screen in the guest, for instance. Regarding the amount of RAM, I’ve run 3 virtual desktops in vmware server on 1GB RAM, but if the host or guests start to swap, then you’re obviously in trouble. You might want to do some research before you publish a comparison of this kind.

  2. Andy Says:


    I did initially try creating VMs with the “Allocate all disk space now” unchecked.

    The performance when doing anything I/O related was dire. I suspect that may be more to do with the server being under-specified and over-loaded.

    Maybe Windows Virtual Server 2003 just happens to deal with overloaded systems better?

    – Andy

  3. Jo-Erlend Schinstad Says:

    Did you install vmware tools in the guest? Did you allocate more RAM to the guest than the host could actually deliver? Because, if you do, then the host will use swap instead of RAM, and as you know, a harddisk isn’t quite as fast as RAM. VMWare Server 1.0.4 is preconfigured to allow some memory to allow some guest vm memory to be swapped. This is a good thing if you know what you’re doing, but will degrade performance radically if abused. It might be better to dedicate a bit less RAM to the guest than to give it too much. I suspect this is the difference between your VMWare Server and MS Virtual Server setups. The point I was trying to make, is that a comparison should compare comparable things.

    If there is a difference in how well the two “deals with overloaded systems”, the difference is not radical. None of them are among the best ,which explains the price tags on them. Virtualization in general has some quirks, though, and small configuration changes can have a huge impact on performance.

  4. Hamlesh Motah Says:

    Biggest latency issue is going to be caused by the lack of direct tick hardware access by the VM. The DL140 G3s in the office are running XEN and can directly access the hardware timer, getting rid of the latency issue :)

    MS Hypervizer/Softgrid (essentially UML but dressed up in Windows land), is really cool, been messing around with it on the office dev server. Application virtualisation is where its at now.

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