I recently had the need to be able to create a VM on a few of our Hyper-V servers at work. I found a great article by The Virtual PC Guy on how to create a new VM. I took what he had and extended the functionality a bit.  To manage Hyper-V, for now, we are pretty much stuck with WMI. However, Virtual Machine Manager will help us out a bunch. In the meantime, we can start with WMI. I figured it never hurts to know what is going on under the hood anyway.

One key piece of functionality that was not included was the ability to override the default location for new VM's when they are created. This is critical to us as we are using a SAN and have dedicated LUN's for our clustered VM's. So now that you have the background, here's the code

   1: function New-HyperVVM {
   2:         param   (
   3:                         [string]$Hypervhost = "localhost",
   4:                         [string]$Vm = "VM Courtesy of PowerShell",
   5:                         [string]$location = "C:MyVirtualMachines$vm"
   6:                         )
   7:         $wmiClassString = "\" + $Hypervhost + "rootvirtualization:Msvm_VirtualSystemGlobalSettingData"
   8:         $wmiclass = [WMIClass]$wmiClassString
   9:         $newVSGlobalSettingData = $wmiClass.CreateInstance()
  10:         $newVSGlobalSettingData.psbase.Properties.Item("ExternalDataRoot").value = $location
  11:         $newVSGlobalSettingData.psbase.Properties.Item("ElementName").value = $Vm
  12:         $VSManagementService = gwmi MSVM_VirtualSystemManagementService -namespace "rootvirtualization" -ComputerName $Hypervhost
  13:         $GlobalSettings  = $newVSGlobalSettingData.psbase.GetText(1)
  14:         $VSManagementService.DefineVirtualSystem($GlobalSettings, $ResourceSettings)
  15: } 

This is up on Poshcode. I highly recommend you be a good PowerShell community member and start sharing your code up here. If you haven't heard about their plans for this site, its awesome!

You can hear Joel and Hal talk about it on this episode of the  PowerScripting podcast.

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