I came across this problem the other day, where I wanted to determine if a Virtual Machine was running on Hyper-V or Virtual Server 2005 host system.

WMI exposes the Win32_ComputerSystem class which contains information about the Manufacturer and Model of a particular system (this is very hand if you want to check type of system before installing an application, e.g. Virtual Machine Additions). The unfortunate news is that Win32_ComputerSystem returns the following on both Hyper-V and Virtual Server hosts:

So how to determine what it is I am looking at? Well there is another WMI class, Win32_BIOS, which can help. Here you can see a difference in the Version between products.

Hyper-V

Virtual Server 2005 SP1

So far this seems to work for me; I am interested if anyone has alternate suggestions on how to solve my little problem, especially if there are cases where this will break (for example limiting the CPU functionality to run NT 4.0?)

Last week I was configuring a lab server with Hyper-V RC0 when I came across this error after creating a Virtual Switch with VLAN ID enabled:

Switch set up failed, name='3742d220-e73d-4ae5-bf0c-429ca168dc41', external port='d02dcb9e-76d4-496a-9c17-ea808e5ce125', internal port='375e5f91-b1fb-415d-8717-cd3ea36c9753', NIC='{165929BF-5BA2-4887-BC54-1D52C1A6BE61}', internal name='07b53c30-5d56-4a2d-a542-146773d39299', internal friendly name='Virtual Network Connection (VLAN Trunk)', error=2147749896, mof code=0.

Located in the Hyper-V application log this error resulted in a failed switch configuration and without a supported way to remove Virtual Switches (doesn’t seem right does it?) prevents you from creating any other network using that interface.

Turns out that this error occurs if you are creating a new network (with VLAN ID enabled) on a physical interface that doesn’t have a default VLAN ID specified, see example image below.

Hyper-V Networking
Hyper-V provides many networking improvements and the Virtual PC Guy’s has put together a great blog post explaining the changes, worth while reading for those making the move from Virtual Server.
Understanding Networking with Hyper-V