CreateSnapshot() does not generate a hyper-v virtual machine snapshot? - c++

Question

HRESULT hr;
IWbemClassObject *pInClass = NULL;
IWbemClassObject *pOutClass = NULL;
IWbemContext *pCtx = 0;
IWbemCallResult *pResult = 0;
BSTR snapshotClassPath = SysAllocString(L"Msvm_VirtualSystemSnapshotService");
hr = m_pWbemServices->GetObject(
snapshotClassPath,
0,
NULL,
&m_pWbemClassObject,
NULL);
if (FAILED(hr))
{
std::cout << "Failed to get class object(Msvm_VirtualSystemSnapshotService). Error code = 0x" << hex << hr << std::endl;
return;
}
// Create snapshot method
BSTR MethodNameOne = SysAllocString(L"CreateSnapshot");
hr = m_pWbemClassObject->GetMethod(
MethodNameOne,
0,
&pInClass,
&pOutClass
);
if (FAILED(hr))
{
std::cout << "Failed to get method(CreateSnapshot). Error code = 0x" << hex << hr << endl;
}
cout << "Succeeded to get method(CreateSnapshot)." << endl;
BSTR virtualSystemSnaphotSettingData = SysAllocString(L"Msvm_VirtualSystemSnapshotSettingData");
// Get the Msvm_VirtualSystemSnapshotSettingData Class object
IWbemClassObject * pvirtualSystemSnaphotSettingData = NULL;
hr = m_pWbemServices->GetObject(
virtualSystemSnaphotSettingData,
0,
pCtx,
&pvirtualSystemSnaphotSettingData,
&pResult
);
if (FAILED(hr))
{
wprintf(L"Error GetObject Msvm_VirtualSystemSnapshotSettingData:0x%08lx\n", hr);
}
std::cout << "Succeeded to get object(Msvm_VirtualSystemSnapshotSettingData)." << std::endl;
// Create instance of Msvm_VirtualSystemSnapshotSettingData class
IWbemClassObject * pInpInstOfSnapshotSettingData = NULL;
hr = pvirtualSystemSnaphotSettingData->SpawnInstance(
0,
&pInpInstOfSnapshotSettingData);
if (FAILED(hr))
{
wprintf(L"Error SpawnInstance Msvm_VirtualSystemSnapshotSettingData:0x%08lx\n", hr);
}
std::cout << "Succeeded to created instance(Msvm_VirtualSystemSnapshotSettingData )." << std::endl;
// Set the property(Consistency Level)
BSTR memberOneForVirtualSystemSnapshotSettingData = SysAllocString(L"ConsistencyLevel");
VARIANT consistencyLevel;
VariantInit(&consistencyLevel);
V_VT(&consistencyLevel) = VT_BSTR;
V_BSTR(&consistencyLevel) = SysAllocString(L"1");
hr = pInpInstOfSnapshotSettingData->Put(
memberOneForVirtualSystemSnapshotSettingData,
0,
&consistencyLevel,
0);
if (FAILED(hr))
{
wprintf(L"Error memberOneForVirtualSystemSnapshotSettingData:0x%08lx\n", hr);
}
wprintf(L"Succeeded to set property(ConsistencyLevel), Consistency level:%s\n", consistencyLevel.bstrVal);
VariantClear(&consistencyLevel);
The CreateSnapshot method was called on Windows Hyper-V 2016 and the execution was successful, but the generated virtual machine snapshot was not visible in the Hyper-V GUI.
// Set the property(ElementName)
BSTR memberThreeForVirtualSystemSnapshotSettingData = SysAllocString(L"ElementName");
VARIANT elementName;
VariantInit(&elementName);
V_VT(&elementName) = VT_BSTR;
V_BSTR(&elementName) = SysAllocString(vmName);
hr = pInpInstOfSnapshotSettingData->Put(
memberThreeForVirtualSystemSnapshotSettingData,
0,
&elementName,
0);
if (FAILED(hr))
{
wprintf(L"Failed to set property(ElementName), Erorr code:0x%08lx\n", hr);
}
wprintf(L"Succeeded to set property(ElementName):%s\n", elementName.bstrVal);
VariantClear(&elementName);
// Set the property(ignore disks that aren't compatible with snapshots)
BSTR memberTwoForVirtualSystemSnapshotSettingData = SysAllocString(L"IgnoreNonSnapshottableDisks");
VARIANT ignoreNonSnapshottableDisks;
ignoreNonSnapshottableDisks.vt = VT_BOOL;
ignoreNonSnapshottableDisks.boolVal = true;
hr = pInpInstOfSnapshotSettingData->Put(
memberTwoForVirtualSystemSnapshotSettingData,
0,
&ignoreNonSnapshottableDisks,
0);
if (FAILED(hr))
{
wprintf(L"Error memberTwoForVirtualSystemSnapshotSettingData:0x%08lx\n", hr);
}
wprintf(L"Succeeded to set property(IgnoreNonSnapshottableDisks):%d\n", ignoreNonSnapshottableDisks.boolVal);
VariantClear(&ignoreNonSnapshottableDisks);
// Create or update instance
hr = m_pWbemServices->PutInstance(
pInpInstOfSnapshotSettingData,
0,
pCtx,
&pResult);
if (FAILED(hr))
{
wprintf(L"Error PutInstance:0x%08lx\n", hr);
}
wprintf(L"Succeeded to update the instance.\n");
// Get textual rendering of the object in the MOF syntax
BSTR objString = NULL;
hr = pInpInstOfSnapshotSettingData->GetObjectText(0, &objString);
if (FAILED(hr))
{
wprintf(L"Error GetObjectText:0x%08lx\n", hr);
}
wprintf(L"Succeeded to get textual rendering.\n");
BSTR ArgNameTwo = SysAllocString(L"SnapshotSettings");
VARIANT v;
V_VT(&v) = VT_BSTR;
V_BSTR(&v) = objString;
wprintf(L"Object text: %s\n", objString);
// Pass the second Argument to CreateSnapshot method
hr = pInClass->Put(ArgNameTwo, 0, &v, 0);
if (FAILED(hr))
{
wprintf(L"Error ArgNameTwo:0x%08lx\n", hr);
}
VariantClear(&v);
wprintf(L"Succeeded to set property(SnapshotSettings).\n");
// set property(AffectedSystem)
VARIANT vtProp;
m_pWbemClassObject->Get(L"__Path", 0, &vtProp, 0, 0);
hr = pInClass->Put(L"AffectedSystem", 0, &vtProp, NULL);
if (FAILED(hr))
{
std::cout << "Failed to set property(AffectedSystem)." << std::endl;
}
wprintf(L"AffectedSystem: %s\n", vtProp.bstrVal);
VariantClear(&vtProp);
// Pass the Third Argument to CreateSnapshot method
BSTR ArgNameThree = SysAllocString(L"SnapshotType");
VARIANT var;
VariantInit(&var);
V_VT(&var) = VT_BSTR;
V_BSTR(&var) = SysAllocString(L"32768");
hr = pInClass->Put(ArgNameThree, 0, &var, 0);
if (FAILED(hr))
{
std::cout << "Failed to set property(SnapshotType)." << std::endl;
}
wprintf(L"SnapshotType: %s\n", var.bstrVal);
VariantClear(&var);
// Call the CreateSnapshot method.
IEnumWbemClassObject* pEnumOb1 = NULL;
hr = m_pWbemServices->ExecQuery(
BSTR(L"WQL"),
BSTR(L"SELECT * FROM Msvm_VirtualSystemSnapshotService"),
WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
NULL,
&pEnumOb1
);
if (FAILED(hr)) {
std::cout << "SELECT * FROM Msvm_VirtualSystemSnapshotService, Error code:0x%08lx" << hex << hr << endl;
}
std::cout << "Succeeded to query snapshot." << std::endl;
IWbemClassObject *pclsObj1 = NULL;
ULONG uReturn1 = 0;
std::cout << "Create snapshot..." << std::endl;
while (1)
{
HRESULT hr = pEnumOb1->Next(WBEM_INFINITE, 1, &pclsObj1, &uReturn1);
if (FAILED(hr) || !uReturn1)
{
break;
}
VARIANT vt;
// Get the value of the path property from Msvm_VirtualSystemSnapshotService Class
hr = pclsObj1->Get(L"__Path", 0, &vt, 0, 0);
if (FAILED(hr))
{
std::wcout << "Failed to get vm's path." << std::endl;
break;
}
wprintf(L"__PATH:%s \n", vt.bstrVal);
//Call the CreateSnapshot method
hr = m_pWbemServices->ExecMethod(
vt.bstrVal,
MethodNameOne,
0,
NULL,
pInClass,
&pOutClass,
NULL);
if (FAILED(hr))
{
wprintf(L"Failed to execute(CreateSnapshot), Erorr code:0x%08lx\n", hr);
break;
}
wprintf(L"Succeeded to create snapshot.\n");
Sleep(10);
pclsObj1->Release();
pclsObj1 = NULL;
}
The return value of ExecMethod() is 0, that is, the call succeeds, but I did not see the snapshot just created on Hyper-V.

Answer 1

I use this PowerShell script and it works. The only problem is to set snapshot name:
function Create-VMSnapshot{
$vm = Get-WmiObject -Namespace $Namespace -ComputerName $ComputerName -Query "select * from msvm_computersystem where elementname='$VMName'"
if($vm -eq $null){
throw "Failed to get VM with display name '$VMName'"
}
$Msvm_VirtualSystemSnapshotService = Get-WmiObject -Namespace $Namespace -ComputerName $ComputerName -Class Msvm_VirtualSystemSnapshotService
if($Msvm_VirtualSystemSnapshotService -eq $null)
{
throw "Failed to get Msvm_VirtualSystemSnapshotService instance"
}
[WMI]$Msvm_VirtualSystemSnapshotSettingData = ([WMIClass]"\\.\root\virtualization\v2:Msvm_VirtualSystemSnapshotSettingData").CreateInstance()
if($Msvm_VirtualSystemSnapshotSettingData -eq $null)
{
throw "Failed to get Msvm_VirtualSystemSnapshotSettingData instance"
}
$Msvm_VirtualSystemSnapshotSettingData.ConsistencyLevel = 1
$Msvm_VirtualSystemSnapshotSettingData.IgnoreNonSnapshottableDisks = $true
$Msvm_VirtualSystemSnapshotSettingData.ElementName = $SnapshotName
$Msvm_VirtualSystemSnapshotSettingData.Description = $SnapshotDescription
$Msvm_VirtualSystemSnapshotSettingData
[System.Management.ManagementBaseObject]$result = $Msvm_VirtualSystemSnapshotService.CreateSnapshot(
$vm,
$Msvm_VirtualSystemSnapshotSettingData.GetText(2),
32768)
[int]$res = Job-Observation -WMIJobResult $result -JobAction "Creating snapshot" -JobProgressCaption "Create snapshot"
$snapshot = (([WMI]$result.Job).GetRelated("Msvm_VirtualSystemSettingData") | % {$_})
$snapshot
}