Hyper-V How To: Create a Differencing VHD using Script


Some friends here on the Hyper-V team shared a PowerShell 2.0 script for creating a diff VHD for your VM:



# Create a differencing VHD


param(
    [string]$newPath = $(throw “Must specify full path for new differencing VHD”),
    [string]$parentPath = $(throw “Must specify full path of parent VHD”)
)


#obtain the Msvm_ImageManagementService class
$ImageMgtService = get-wmiobject -class “Msvm_ImageManagementService” -namespace “root\virtualization”


# Create the fixed VHD
$result = $ImageMgtService.CreateDifferencingVirtualHardDisk($newPath,$parentPath)


if($result.ReturnValue -eq 4096){
    # A Job was started, and can be tracked using its Msvm_Job instance
    $job = [wmi]$result.Job
    # Wait for job to finish
    while($job.jobstate -lt 7){$job.get()}
    # Return the Job’s error code
    return $job.ErrorCode
}
# Otherwise, the method completed
return $result.ReturnValue


 




For more info on how to use PS cmdlets see: http://www.microsoft.com/technet/scriptcenter/topics/msh/cmdlets/index.mspx


See also James O’Neil’s New and improved PowerShell Library for Hyper-V. Now with more functions and… documentation!


For all 35 sample Hyper-V PS1 scripts in a zipfile, go to: Hyper-V PowerShell Example Scripts.zip-download

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