Hyper-V WMI: What VHD’s/Physical Disks Are Associated With a Virtual Machine?


I  got a great question based on yesterday’s post (by the way my e-mail was blocking a lot of external messages that’s fixed now so I apologize to anyone I missed a mail from).  The person was asking how they could figure out what physical disk a virtual machine is using when configured for passthough on the host…  Well here’s the magic – I took it a little further and got the path’s for any attached VHD’s…  Enjoy!

 

$HyperVParent = "localhost"
$HyperVGuest = "My Virtual Machine"

$VMManagementService = Get-WmiObject -class "Msvm_VirtualSystemManagementService" -namespace "root\virtualization" -ComputerName $HyperVParent
$Vm = Get-WmiObject -Namespace "root\virtualization" -ComputerName $HyperVParent -Query "Select * From Msvm_ComputerSystem Where ElementName=’$HyperVGuest’"
$VMSettingData = Get-WmiObject -Namespace "root\virtualization" -Query "Associators of {$Vm} Where ResultClass=Msvm_VirtualSystemSettingData AssocClass=Msvm_SettingsDefineState" -ComputerName $HyperVParent

#
#Getting the Path’s for Attached VHD’s
$VirtualDiskResource = Get-WmiObject -Namespace "root\virtualization" `
   
-Query "Associators of {$VMSettingData} Where ResultClass=Msvm_ResourceAllocationSettingData AssocClass=Msvm_VirtualSystemSettingDataComponent" `
   
-ComputerName $HyperVParent | Where-Object { $_.ResourceSubType -match "Microsoft Virtual Hard Disk" }
    
ForEach-Object -InputObject $VirtualDiskResource -Process {
   
Write-Host "Virtual Hard Disk At: $_.Connection[0]"
}

#
#Getting the Disk Attachments for Passthrough Disks
$PhysicalDiskResource = Get-WmiObject -Namespace "root\virtualization" `
   
-Query "Associators of {$VMSettingData} Where ResultClass=Msvm_ResourceAllocationSettingData AssocClass=Msvm_VirtualSystemSettingDataComponent" `
   
-ComputerName $HyperVParent | Where-Object { $_.ResourceSubType -match "Microsoft Physical Disk Drive" }
    
ForEach-Object -InputObject $PhysicalDiskResource -Process {
   
Write-Host "Passthrough Disk At: " ([WMI]$_.HostResource[0]).ElementName
   
Write-Host "Passthrough Disk Drive Number: " ([WMI]$_.HostResource[0]).DriveNumber
}

 

Taylor Brown
Hyper-V Integration Test Lead
http://blogs.msdn.com/taylorb

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Comments (7)

  1. Very handy script by Taylor Brown I got a great question based on yesterday’s post (by the way my e-mail

  2. tony says:

    You are asking Hyper-V parent’s Hyper-V WMI provider to answer which one is VHD / passthrough disk.

    Without asking parent, how to detect?

     

    =========================================
    Without asking the parent you can’t detect this information.

    -Taylor

  3. Niall Waller says:

    If anyone is trying to do this in VBScript then here’s the code:

    strComputer = ""

    Set objWMIService = GetObject("winmgmts:\" & strComputer & "rootvirtualization")

    Set colSystems = objWMIService.ExecQuery("SELECT * FROM Msvm_VirtualSystemSettingData", _

                                          "WQL", wbemFlagReturnImmediately + wbemFlagForwardOnly)

    For Each objSystem In colSystems

      WScript.Echo "ElementName: " & objSystem.ElementName

      Set colResData = objWMIService.ExecQuery("Associators of {Msvm_VirtualSystemSettingData=’" & objSystem.InstanceID & "’} Where ResultClass=Msvm_ResourceAllocationSettingData AssocClass=Msvm_VirtualSystemSettingDataComponent", _

                                          "WQL", wbemFlagReturnImmediately + wbemFlagForwardOnly)

      For Each objResData In colResData

         If objResData.ResourceSubType = "Microsoft Virtual Hard Disk" Then

            strConnection = Join(objResData.Connection, ",")

            WScript.Echo "  Connection: " & strConnection

         End If

      Next

    Next

  4. This is a follow up on my previous post on Hyper-V WMI: What VHD’s/Physical Disks Are Associated With

  5. sem says:

    is there an easy way to determine the type of a virtual disk – ie. fixed, dynamic, differencing?

    and if differencing – what is the parent?

  6. Jester says:

    First of all thank you for putting together this script. I am somewhat of a novice with powershell scripts and am having an issue determining why I am getting the results back that I am getting. I am trying to run this script against a host with 50+ passthrough disks and a vm that uses 4 or 5 of those disks. I only get results for the first disk. I see the last function in the script is to loop through, but its only returning the first listed disk