CompactVirtualHardDisk method of the Msvm_ImageManagementService class

Compacts a dynamic virtual hard disk file. Compacting is the process of unallocating unused portions of the virtual hard disk.

Syntax

uint32 CompactVirtualHardDisk(
  [in]  string              Path,
  [out] CIM_ConcreteJob REF Job
);

Parameters

Path [in]

Type: string

A fully qualified path that specifies the location of the merging file.

Job [out]

Type: CIM_ConcreteJob

A reference to the job (can be null if the task is completed).

Return value

Type: uint32

This method can return one of the following values.

Completed with No Error (0)

Method Parameters Checked - Job Started (4096)

Failed (32768)

Access Denied (32769)

Not Supported (32770)

Status is unknown (32771)

Timeout (32772)

Invalid parameter (32773)

System is in used (32774)

Invalid state for this operation (32775)

Incorrect data type (32776)

System is not available (32777)

Out of memory (32778)

File not found (32779)

Remarks

Access to the Msvm_ImageManagementService class might be restricted by UAC Filtering. For more information, see User Account Control and WMI.

Examples

The following C# example compacts a virtual hard disk. The referenced utilities can be found in Common Utilities for the Virtualization Samples.

using System;
using System.Management;

namespace HyperVSamples
{
    class CompactVHD
    {
        /// <summary>
        /// Compact a virtual hard disk
        /// </summary>
        static void CompactVirtualHardDisk(string vhdPath)
        {
            ManagementScope scope = new ManagementScope(@"root\virtualization", null);
            ManagementObject imageService = Utility.GetServiceObject(scope, "Msvm_ImageManagementService");

            ManagementBaseObject inParams = imageService.GetMethodParameters("CompactVirtualHardDisk");
            inParams["Path"] = vhdPath;
            ManagementBaseObject outParams = imageService.InvokeMethod("CompactVirtualHardDisk", inParams, null);
            if ((UInt32)outParams["ReturnValue"] == ReturnCode.Started)
            {
                if (Utility.JobCompleted(outParams, scope))
                {
                    Console.WriteLine("{0} was compacted successfully.", inParams["Path"]);
                }
                else
                {
                    Console.WriteLine("Unable to compact {0}", inParams["Path"]);
                }
            }
            else
            {
                Console.WriteLine("Compact {0} returned error {1}", inParams["Path"], outParams["ReturnValue"]);
            }

            inParams.Dispose();
            outParams.Dispose();
            imageService.Dispose();
        }

        static void Main(string[] args)
        {
            if (args != null &amp;&amp; args.Length != 1)
            {
                Console.WriteLine("Usage: CompactVHD vhdPath");
                return;
            }
            CompactVirtualHardDisk(args[0]);
        }
    }
}

The following VBScript example compacts a virtual hard disk.

option explicit 

dim objWMIService
dim managementService
dim fileSystem

const JobStarting = 3
const JobRunning = 4
const JobCompleted = 7
const wmiStarted = 4096


Main()

'-----------------------------------------------------------------
' Main
'-----------------------------------------------------------------
Sub Main()
    dim computer, objArgs, vhdPath
    
    set fileSystem = Wscript.CreateObject("Scripting.FileSystemObject")

    computer = "."
    set objWMIService = GetObject(Format1("winmgmts:\\{0}\root\virtualization", computer))
    set managementService = objWMIService.ExecQuery("Select * from Msvm_ImageManagementService").ItemIndex(0)


    set objArgs = WScript.Arguments
    if WScript.Arguments.Count = 1 then
       vhdPath = objArgs.Unnamed.Item(0)
    else
       WScript.Echo "usage: cscript CompactVHD.vbs path"
       WScript.Quit(1)
    end if

    if CompactVHD(vhdPath) then
        WriteLog "Done"
        WScript.Quit(0)
    else
        WriteLog "CompactVHD failed"
        WScript.Quit(1)
    end if
End Sub

'-----------------------------------------------------------------
' Execute CompactVirtualHardDisk
'-----------------------------------------------------------------
Function CompactVHD(vhdPath)
    WriteLog Format1("Function CompactVHD({0})",  vhdPath)
    
    dim objInParam, objOutParams

    CompactVHD = false

    set objInParam = managementService.Methods_("CompactVirtualHardDisk").InParameters.SpawnInstance_()
    objInParam.Path = vhdPath

    set objOutParams = managementService.ExecMethod_("CompactVirtualHardDisk", objInParam)

    if (WMIMethodStarted(objOutParams)) then
        if (WMIJobCompleted(objOutParams)) then
            WriteLog Format1("VHD {0} was compacted successfully", vhdPath)
            CompactVHD = true
        end if
    end if

End Function


'-----------------------------------------------------------------
' Handle wmi return values
'-----------------------------------------------------------------
Function WMIMethodStarted(outParam)
    WriteLog "Function WMIMethodStarted"
    
    dim wmiStatus
    
    WMIMethodStarted = false

    if Not IsNull(outParam) then
        wmiStatus = outParam.ReturnValue

        if  wmiStatus = wmiStarted then
            WMIMethodStarted = true
        else
            WriteLog Format1("Compact VHD failed with error {0}", wmiStatus)
        end if
   end if

End Function

'-----------------------------------------------------------------
' Handle wmi Job object
'-----------------------------------------------------------------
Function WMIJobCompleted(outParam)
    WriteLog "Function WMIJobCompleted"
    
    dim WMIJob, jobState

    set WMIJob = objWMIService.Get(outParam.Job)

    WMIJobCompleted = true

    jobState = WMIJob.JobState

    while jobState = JobRunning or jobState = JobStarting
        WriteLog Format1("In progress... {0}% completed.",WMIJob.PercentComplete)
        WScript.Sleep(1000)
        set WMIJob = objWMIService.Get(outParam.Job)
        jobState = WMIJob.JobState
    wend

    if (jobState <> JobCompleted) then
        WriteLog Format1("ErrorCode:{0}", WMIJob.ErrorCode)
        WriteLog Format1("ErrorDescription:{0}", WMIJob.ErrorDescription)
        WMIJobCompleted = false
    end if

End Function

'-----------------------------------------------------------------
' Create the console log files.
'-----------------------------------------------------------------
Sub WriteLog(line)
    dim fileStream
    set fileStream = fileSystem.OpenTextFile(".\CompactVHD.log", 8, true)
    WScript.Echo line
    fileStream.WriteLine line
    fileStream.Close

End Sub

'------------------------------------------------------------------------------
' The string formatting functions to avoid string concatenation.
'------------------------------------------------------------------------------
Function Format1(myString, arg0)
    Format1 = Replace(myString, "{0}", arg0)
End Function

Requirements

See also

CompactVirtualHardDisk (V2)

CIM_ConcreteJob

Msvm_ImageManagementService