Starting a Hyper-V Virtual Machine

Ben Armstrong [MSFT]

30 Jan 2008 2:24 AM

Comments 6

Next in the line up of scripts - another simple one - starting a virtual machine:

VBScript:

     Option Explicit

    Dim WMIService

    Dim VMList

    Dim VMName

    'Specify the name of the virtual machine that I want to start

    VMName = "Windows Server 2003"

    'Get instance of 'virtualization' WMI service on the local computer

    Set WMIService = GetObject("winmgmts:\\.\root\virtualization")

    'Query for the specific virtual machine that I want to start

    Set VMList = WMIService.ExecQuery("SELECT * FROM Msvm_ComputerSystem WHERE ElementName='" & VMName & "'")

    ' Request a state change on the first VM that is returned

    ' 2 = start, 3 = stop and 32769 = save state

    VMList.ItemIndex(0).RequestStateChange(2)

PowerShell:

    #The name of the virtual machine to be started

    $VMName = "Windows Server 2003"

    #Get the VM Object

    $query = "SELECT * FROM Msvm_ComputerSystem WHERE ElementName='" + $VMName + "'"

    $VM = get-wmiobject -query $query -namespace "root\virtualization" -computername "."

    #Request a state change on the VM

    $Result = $VM.RequestStateChange(2)

Now for some notes:

Under VBScript a WMIService.ExecQuery will always return a collection, even if there is only one result. Using ItemIndex(0) allows you to assume that there is only one item in the collection and just act on it.
PowerShell will return a collection for multiple results, but an object if there is a single result. This can actually be a bit trickier to deal with if you have to handle both.
Since I am querying on the element name - it is actually possible to get multiple virtual machines back (you would need to have two virtual machines with the same name for this to happen). I am not handling this case here.

Cheers,
Ben