PowerShell Script for Exporting a virtual machine

Even though it might be tempting just to copy a whole virtual machine from Hyper-V Host to Hyper-V Host, this is not the way to do it. Importing and Exporting Hyper-V-style is. This post provides a PowerShell script to make it easier.

I need to automate the process of exporting a virtual machine recently – and when I checked around I found that while there are a number of sample scripts out there that show you how to do this (some even on this blog) they are all written in VBScript.  As I am now to the stage where PowerShell is my preferred scripting language – I sat down and wrote up this short script:

# Function for handling WMI jobs / return values

Function ProcessResult($result, $successString, $failureString)

{

   #Return success if the return value is "0"

   if ($result.ReturnValue -eq 0)

      {write-host $successString} 

   #If the return value is not "0" or "4096" then the operation failed

   ElseIf ($result.ReturnValue -ne 4096)

      {write-host $failureString " Error value:" $result.ReturnValue}

   Else

      {#Get the job object

      $job=[WMI]$result.job

      #Provide updates if the jobstate is "3" (starting) or "4" (running)

      while ($job.JobState -eq 3 -or $job.JobState -eq 4)

         {write-host $job.PercentComplete "% complete"

          start-sleep 1

          #Refresh the job object

          $job=[WMI]$result.job}

       #A jobstate of "7" means success

       if ($job.JobState -eq 7)

          {write-host $successString

          return $true}

       Else

          {write-host $failureString

          write-host "ErrorCode:" $job.ErrorCode

          write-host "ErrorDescription" $job.ErrorDescription

          return $false}

       }

}

# Prompt for the Hyper-V Server to use

$HyperVServer = Read-Host "Specify the Hyper-V Server to use (enter '.' for the local computer)"

# Prompt for the virtual machine to use

$VMName = Read-Host "Specify the name of the virtual machine"

# Prompt for the path to export to

$ExportPath = Read-Host "Specify the path to place the exported virtual in"

# Get the management service

$VMMS = gwmi -namespace root\virtualization Msvm_VirtualSystemManagementService -computername $HyperVServer

# Get the virtual machine object

$VM = gwmi MSVM_ComputerSystem -filter "ElementName='$VMName'" -namespace "root\virtualization" -computername $HyperVServer

# Export the virtual machine

$result = $VMMS.ExportVirtualSystem($VM, $true, $ExportPath)

# Check to make sure we succeeded

$exportSucceeded = ProcessResult $result "Virtual machine exported." "Failed to export virtual machine."

Some quick notes to make about this script:

• This script takes a Hyper-V server name, a virtual machine name and an export path – and then performs a full export to the requested location.
• I am using the older (deprecated) ExportVirtualSystem method here – and not ExportVirtualSystemEx (which I really should do).  The main reason for this is that while ExportVirtualSystemEx is a lot more powerful than ExportVirtualSystem, ExportVirtualSystem works perfectly fine for this basic use case and is much easier to script.

Source and download: http://blogs.msdn.com/b/virtual_pc_guy/archive/2012/02/08/powershell-script-for-exporting-a-virtual-machine.aspx

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