ExpandVirtualHardDisk method of the Msvm_ImageManagementService class

Expands an existing virtual hard disk (.vhd) file. If the disk image is already attached to the virtual machine, it will send notifications to the running virtual machine about disk expansion.


uint32 ExpandVirtualHardDisk(
  [in]  string              Path,
  [in]  uint64              MaxInternalSize,
  [out] CIM_ConcreteJob REF Job


Path [in]

Type: string

A fully qualified path that specifies the location of the disk image file.

MaxInternalSize [in]

Type: uint64

The maximum size of the virtual hard disk as viewable by the virtual machine, in bytes. MaxInternalSize minimum value is DiskSize + 512 - (DiskSize mod 512). DiskSize is the disk image file in number of bytes. The InvalidParameter error (32773) is returned if the MaxInternalSize value specified is less than the minimum value.

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)


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


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

using System;
using System.Management;
namespace HyperVSamples
    public class ExpandVirtualHardDiskClass
        const UInt64 Size1G = 0x40000000;

        public static void ExpandVirtualHardDisk(string path, UInt64 maxInternalSize)
            ManagementScope scope = new ManagementScope(@"root\virtualization", null);
            ManagementObject imageService = Utility.GetServiceObject(scope, "Msvm_ImageManagementService");

            ManagementBaseObject inParams = imageService.GetMethodParameters("ExpandVirtualHardDisk");
            inParams["Path"] = path;
            inParams["MaxInternalSize"] = maxInternalSize * Size1G;
            ManagementBaseObject outParams = imageService.InvokeMethod("ExpandVirtualHardDisk", inParams, null);
            if ((UInt32)outParams["ReturnValue"] == ReturnCode.Started)
                if (Utility.JobCompleted(outParams, scope))
                    Console.WriteLine("{0} was expanded successfully.", inParams["Path"]);
                    Console.WriteLine("Unable to expand {0}", inParams["Path"]);

        static void Main(string[] args)
            if (args != null && args.Length != 2)
                Console.WriteLine("Usage: ExpandVHD path, maxInternalSize");
                Console.WriteLine("maxInternalSize: unit in 1 gigabyte");
            string path = args[0];
            UInt64 maxInternalSize = UInt64.Parse(args[1]);
            ExpandVirtualHardDisk(path, maxInternalSize);

The following VBScript example expands a virtual hard disk file.

option explicit

dim objWMIService
dim managementService
dim fileSystem

const Size1G = &H40000000

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


' Main
Sub Main()

    dim path, maxInternalSize, objArgs, computer
    set fileSystem = Wscript.CreateObject("Scripting.FileSystemObject")

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

    set objArgs = WScript.Arguments
    if WScript.Arguments.Count = 2 then
       path = objArgs.Unnamed.Item(0)
       maxInternalSize = objArgs.Unnamed.Item(1)
       WScript.Echo "usage: cscript ExpandVHD.vbs Path MaxInternalSize"
       WScript.Echo "MaxInternalSize: unit in Gigabytes"
    end if

    if ExpandVirtualHardDisk(path, maxInternalSize) then
        WriteLog "Done"
        WriteLog "ExpandVHD failed"
    end if

End Sub

' Execute ExpandVirtualHardDisk
Function ExpandVirtualHardDisk(path, maxInternalSize)
    WriteLog Format2("Sub ExpandVirtualHardDisk({0}, {1})",  Path, maxInternalSize)

    dim objInParam, objOutParams
    ExpandVirtualHardDisk = false

    set objInParam = managementService.Methods_("ExpandVirtualHardDisk").InParameters.SpawnInstance_()
    objInParam.Path = Path
    objInParam.MaxInternalSize = maxInternalSize * Size1G

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

    if (WMIMethodStarted(objOutParams)) then
        if (WMIJobCompleted(objOutParams)) then
            WriteLog Format2("{0} was expected to {1} gigabytes.", Path, MaxInternalSize)
            ExpandVirtualHardDisk = 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
            WriteLog Format3("Expand VHD {0} to {1} failed. The operation was not able to create ConcreteJob object. Error {2}", Path, MaxInternalSize, 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)
        set WMIJob = objWMIService.Get(outParam.Job)
        jobState = WMIJob.JobState

    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(".\ExpandVHD.log", 8, true)
    WScript.Echo line
    fileStream.WriteLine line

End Sub

' The string formatting functions to avoid string concatenation.
Function Format2(myString, arg0, arg1)
    Format2 = Format1(myString, arg0)
    Format2 = Replace(Format2, "{1}", arg1)
End Function

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


Minimum supported client
None supported
Minimum supported server
Windows Server 2008
End of client support
None supported
End of server support
Windows Server 2012

See also

ResizeVirtualHardDisk (V2)