ClusterPrepareSharedVolumeForBackup() fails on Window 2012 CSV

Question

I've a Windows sever 2012 RC Hyper-V cluster with VM using CSV. There I'm seeing ClusterPrepareSharedVolumeForBackup() failing with error ERROR_INVALID_PARAMETER. It works fine on 2008 r2. Any idea what could be the issue here.

Answer 1

Hi Subhasish,
In your previous post, you have mentioned that no special logic is needed to track CSV backup process in Server 2012 and later OSes. That means, the same VSS procedure that used to snapshot non-CSV Hyper-V setup would be enough? For me, I am not getting
any errors during the VSS snapshot process but the writer status changed to VSS_WS_FAILED_AT_PREPARE_SNAPSHOT in the backup node and my CSV backup code failed with VHD sharing violation error (Error 32) during backup. The same code works fine in non-CSV Hyper-V
backup.
Error:
WRITER "Microsoft Hyper-V VSS Writer"
Status: 8 (VSS_WS_FAILED_AT_PREPARE_SNAPSHOT)
Writer failure code: 0x800423f0 (VSS_E_WRITERERROR_INCONSISTENTSNAPSHOT)
====================My pseudo code (Hyper-V VSS snapshot)====================
CreateVssBackupComponents();
VssBackupComp->InitializeForBackup();
VssBackupComp->SetBackupState(true, true, VSS_BT_FULL, false);
VssBackupComp->SetContext(VSS_CTX_BACKUP | VSS_CTX_CLIENT_ACCESSIBLE_WRITERS | VSS_CTX_APP_ROLLBACK);
// Hyper-V VSS writer
wchar_t* clsid_str = L"{66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}";
CLSIDFromString(clsid_str, &HypervWriterGuid);
pVssBackupComp->EnableWriterClasses((const VSS_ID *)&HypervWriterGuid, 1);
pVssBackupComp->GatherWriterMetadata(&m_pVssWriterMetaDataAsync);
_tprintf(_T("Gathering Metadata from Writers...\n"));
hResult = m_pVssWriterMetaDataAsync->Wait();
// Add Hyper-V VM component
// Get writer Metadata Count
pVssBackupComp->GetWriterMetadataCount(&uTotalWriters);
// Enumerate writers...
 for(uWriter = 0; uWriter < uTotalWriters; uWriter++)
 Get the metadata for this writer
 Get Writer Identity()
 GetComponentInfo()
 AddComponent() // ComponentName==>VM Name
pVssBackupComp->StartSnapshotSet(&SnapshotSetId);
pVssBackupComp->AddToSnapshotSet(szVolumeDriveLetter, GUID_NULL, &SnapshotSetId); // szVolumeDriveLetter==>C:\
pVssBackupComp->PrepareForBackup(&m_pVssPrepareAsync);
m_pVssPrepareAsync->Wait();
pVssBackupComp->DoSnapshotSet(&m_pVssDoShadowCopy);
m_pVssDoShadowCopy->Wait();
======================================================================
I am wondering, Do I need to use any writers other than Hyper-V VSS writer or need to use any other provider ID? My volume folder name is C:\ClusterStorage\Volume1.
I couldn't find much information about CSV and 2012 VSS implementation. I've also posted in Hyper-V forum few days back but didn't get any reply.
http://social.technet.microsoft.com/Forums/windowsserver/en-US/2bac4837-01b6-4956-a307-99c6c086e442/hyperv-csv-2012-backup-developer-documentation?forum=winserverhyperv
I am new to CSV and tt would be really helpful if you can explain this.
Thanks in Advance.