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RequestStateChange method of the Msvm_ComputerSystem class

Hyper-V

Requests that the state of the computer system be changed to the value specified in the RequestedState parameter. Invoking the RequestStateChange method multiple times could result in earlier requests being overwritten or lost. If 0 is returned, then the task completed successfully. Any other return code indicates an error condition.

While the state change is in progress, the RequestedState property is changed to the value of the RequestedState parameter.

Syntax


uint32 RequestStateChange(
  [in]   uint16 RequestedState,
  [out]  CIM_ConcreteJob REF Job,
  [in]   datetime TimeoutPeriod
);

Parameters

RequestedState [in]

Type: uint16

The new state. The following are possible values.

ValueMeaning
Enabled
2

Turns the VM on.

Disabled
3

Turns the VM off.

Reboot
10

A hard reset of the VM.

Reset
11

For future use.

DMTF Reserved
13–32767

Reserved.

Paused
32768

Pauses the VM.

Suspended
32769

Saves the state of the VM.

Vendor Reserved
32770–65535

Reserved.

 

Job [out]

Type: CIM_ConcreteJob

An optional reference to CIM_ConcreteJob that is returned if the operation is executed asynchronously. If present, the returned reference can be used to monitor progress and obtain the result of the method.

TimeoutPeriod [in]

Type: datetime

A timeout period that specifies the maximum amount of time that the client expects the transition to the new state to take. The interval format must be used to specify the timeout period. A value of 0 or a null parameter indicates that the client has no time requirements for the transition. If this property does not contain 0 or null and the implementation does not support this parameter, a return code of "Use Of Timeout Parameter Not Supported" must be returned.

Return value

Type: uint32

This method returns one of the following values.

Completed with No Error (0)
DMTF Reserved (7–4095)
Method Parameters Checked - Transition Started (4096)
Failed (32768)
Access Denied (32769)
Not Supported (32770)
Status is unknown (32771)
Timeout (32772)
Invalid parameter (32773)
System is in use (32774)
Invalid state for this operation (32775)
Incorrect data type (32776)
System is not available (32777)
Out of memory (32778)

Remarks

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

Examples

The following C# example starts or disables a virtual machine. The referenced utilities can be found in Common Utilities for the Virtualization Samples.

Important  To function correctly, the following code must be run on the VM host server, and must be run with Administrator privileges.



using System;
using System.Management;

namespace HyperVSamples
{
    public class RequestStateChangeClass
    {
        public static void RequestStateChange(string vmName, string action)
        {
            ManagementScope scope = new ManagementScope(@"\\.\root\virtualization", null);
            ManagementObject vm = Utility.GetTargetComputer(vmName, scope);

            if (null == vm)
            {
                throw new ArgumentException(
                    string.Format(
                    "The virtual machine '{0}' could not be found.", 
                    vmName));
            }

            ManagementBaseObject inParams = vm.GetMethodParameters("RequestStateChange");

            const int Enabled = 2;
            const int Disabled = 3;

            if (action.ToLower() == "start")
            {
                inParams["RequestedState"] = Enabled;
            }
            else if (action.ToLower() == "stop")
            {
                inParams["RequestedState"] = Disabled;
            }
            else
            {
                throw new Exception("Wrong action is specified");
            }

            ManagementBaseObject outParams = vm.InvokeMethod(
                "RequestStateChange", 
                inParams, 
                null);

            if ((UInt32)outParams["ReturnValue"] == ReturnCode.Started)
            {
                if (Utility.JobCompleted(outParams, scope))
                {
                    Console.WriteLine(
                        "{0} state was changed successfully.", 
                        vmName);
                }
                else
                {
                    Console.WriteLine("Failed to change virtual system state");
                }
            }
            else if ((UInt32)outParams["ReturnValue"] == ReturnCode.Completed)
            {
                Console.WriteLine(
                    "{0} state was changed successfully.", 
                    vmName);
            }
            else
            {
                Console.WriteLine(
                    "Change virtual system state failed with error {0}", 
                    outParams["ReturnValue"]);
            }

        }

        public static void Main(string[] args)
        {
            if (args != null && args.Length != 2)
            {
                Console.WriteLine("Usage: <application> vmName action");
                Console.WriteLine("action: start|stop");
                return;
            }

            RequestStateChange(args[0], args[1]);
        }

    }
}


The following VBScript example starts or disables a virtual machine.

Important  To function correctly, the following code must be run on the VM host server, and must be run with Administrator privileges.



dim objWMIService
dim fileSystem

const JobStarting = 3
const JobRunning = 4
const JobCompleted = 7
const wmiStarted = 4096
const Enabled = 2
const Disabled = 3



Main()

'-----------------------------------------------------------------
' Main routine
'-----------------------------------------------------------------
Sub Main()
    set fileSystem = Wscript.CreateObject("Scripting.FileSystemObject")

    strComputer = "."
    set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\virtualization")

    set objArgs = WScript.Arguments
    if WScript.Arguments.Count = 2 then
       vmName= objArgs.Unnamed.Item(0)
       action = objArgs.Unnamed.Item(1)
    else
       WScript.Echo "usage: cscript StartVM.vbs vmName start|stop"
       WScript.Quit
    end if
    
    set computerSystem = GetComputerSystem(vmName)

    if RequestStateChange(computerSystem, action) then

        WriteLog "Done"
        WScript.Quit(0)
    else
        WriteLog "RequestStateChange failed"
        WScript.Quit(1)
    end if

End Sub

'-----------------------------------------------------------------
' Retrieve Msvm_VirtualComputerSystem from base on its ElementName
' 
'-----------------------------------------------------------------
Function GetComputerSystem(vmElementName)
    On Error Resume Next
    query = Format1("select * from Msvm_ComputerSystem where ElementName = '{0}'", vmElementName)
    set GetComputerSystem = objWMIService.ExecQuery(query).ItemIndex(0)
    if (Err.Number <> 0) then
        WriteLog Format1("Err.Number: {0}", Err.Number)
        WriteLog Format1("Err.Description:{0}",Err.Description)
        WScript.Quit(1)
    end if
End Function


'-----------------------------------------------------------------
' Turn on a virtual machine
'-----------------------------------------------------------------
Function RequestStateChange(computerSystem, action)
    WriteLog Format2("RequestStateChange({0}, {1})", computerSystem.ElementName, action)

    RequestStateChange = false
    set objInParam = computerSystem.Methods_("RequestStateChange").InParameters.SpawnInstance_()
    
    if action = "start" then
        objInParam.RequestedState = Enabled
    else
        objInParam.RequestedState = Disabled
    end if

    set objOutParams = computerSystem.ExecMethod_("RequestStateChange", objInParam)

    if (WMIMethodStarted(objOutParams)) then
        if (WMIJobCompleted(objOutParams)) then
            WriteLog Format1("VM {0} was started successfully", computerSystem.ElementName)
            RequestStateChange = true
        end if
    end if

End Function


'-----------------------------------------------------------------
' Handle wmi return values
'-----------------------------------------------------------------
Function WMIMethodStarted(outParam)

    WMIMethodStarted = false

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

        if  wmiStatus = wmiStarted then
            WMIMethodStarted = true
        end if

    end if

End Function


'-----------------------------------------------------------------
' Handle wmi Job object
'-----------------------------------------------------------------
Function WMIJobCompleted(outParam)
    dim WMIJob

    set WMIJob = objWMIService.Get(outParam.Job)

    WMIJobCompleted = true

    jobState = WMIJob.JobState

    while jobState = JobRunning or jobState = JobStarting

        WScript.Sleep(1000)
        set WMIJob = objWMIService.Get(outParam.Job)
        jobState = WMIJob.JobState

    wend


    if (jobState <> JobCompleted) then
        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(".\StartVM.log", 8, true)
    WScript.Echo line
    fileStream.WriteLine line
    fileStream.Close

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


Requirements

Minimum supported client

None supported

Minimum supported server

Windows Server 2008

End of client support

None supported

End of server support

Windows Server 2012

Namespace

\\.\Root\Virtualization

MOF

WindowsVirtualization.mof

See also

Msvm_ComputerSystem

 

 

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