Prerequisites and Known Issues with Hyper-V Protection

Prerequisites and Known Issues with...

Updated: February 1, 2010

Applies To: System Center Data Protection Manager 2007

Prerequisites for protecting Hyper-V using DPM 2007 SP1

Before protecting Hyper-V virtual machines with DPM, ensure that the following updates are installed on the target Hyper-V server:

The customer should be running Hyper-V RTM. The corresponding Windows update is KB950050 (http://go.microsoft.com/fwlink/?LinkID=132735).
Install the following updates:
- KB951308 (http://go.microsoft.com/fwlink/?LinkID=132733) on each cluster node for cluster deployment.
  Increased functionality and virtual machine control in the Windows Server 2008 Failover Cluster Management console for the Hyper-V role.
- KB956697 (http://go.microsoft.com/fwlink/?LinkID=133781). This update may be applied when the Hyper-V writer seems to go missing due to the presence of corrupt Virtual Machine configuration files in the Hyper-V Server.
- KB958184 (http://go.microsoft.com/fwlink/?LinkId=143332). This update may be applied when virtual machine files are saved on a volume mounted on a failover cluster using a volume GUID.
- KB959962 (http://go.microsoft.com/fwlink/?LinkId=136583) on the Hyper-V hosts. This update for Hyper-V writer is required if the backup fails for one of the following reasons:
  - Retryable VSS error.
  - VSS application writer provider is going to bad state.
  - If recovery of a virtual machine is failing because it has legacy network adapters attached.
  Following this update, the integration services on each of the virtual machines running on the server must be updated by inserting the Integration Services Disk from the Action menu in the virtual machine’s management console. This will require the virtual machine to restart.
- KB960038 (http://go.microsoft.com/fwlink/?LinkId=136584) on all Hyper-V hosts. This update for Windows Server 2008 fixes a crash of the Hyper-V host server which you may experience when backups are made using Hyper-V writer.
The version of Integration Components running inside the VM should be the same as the version of Hyper-V on the host. For Hyper-V RTM it is 6.0.6001.18016.
You can confirm this in the Device Manager inside the guest VM. Under System Devices in Device Manager, right-click the entry Hyper-V Volume Shadow Copy and choose Properties. Check the version under the Driver tab. If the version does not match, insert the integration services disk by choosing the option under the Action menu in the VM console. Install the integration components and reboot the VM.

Known Issues

Issue	Symptoms	Cause	Workaround	Solution	Recommendation
Hyper-V server stops working when DPM runs backups on the server.	You may experience a Stop 0x7E when you backup a server that has the Hyper-V role installed.	This is a problem in the volsnap.sys driver when interacting with the Hyper-V VSS writer.	N/A	Download and install KB960038 on the Hyper-V host to solve this problem.	We recommend that you deploy this in the next available downtime window on the Hyper-V host.
Backup of Hyper-V virtual machine fails	Hyper-V virtual machine backups (backups using child partition) fail with following error for multiple volume virtual machines: DPM encountered a retryable VSS error. (ID 30112 Details: Unknown error (0x800423f3) (0x800423F3)). On the Hyper-V host in the event log: VMMS Event log contains following entry: Failed to revert to VSS snapshot on one or more virtual hard disks of the virtual machine '%1'. (Virtual machine ID %2).	.	Perform an offline backup of the virtual machine.	Download and install KB959962 on the Hyper-V host to solve this problem.	We recommend that you install this update on all Hyper-V hosts protected by DPM.
Recovery of Hyper-V virtual machine fails	The Hyper-V Virtual Machine Management service stops when you are restoring a virtual machine.	This issue can occur if the virtual machine is configured to use a legacy network adapter.	Restart the Hyper-V Virtual Machine Management service.	Download and install KB959962 on the Hyper-V host to solve this problem. Then recover the data to an alternate location.	We recommend that you deploy this update on all Hyper-V hosts protected by DPM.
Backup of the Hyper-V virtual machine fails	Hyper-V VSS writer is in a bad state and does not identify itself to VSS anymore. The VSS application writer or the VSS provider is in a bad state. Either it was already in a bad state or it entered a bad state during the current operation (ID 30111 Details: Unknown error (0x80042319) (0x80042319)). Please check that the Event Service and the VSS service are running, and check for errors associated with these services in the Application Event Log on the server hyper01.contoso.com. Please allow 10 minutes for VSS to repair itself and then retry the operation.	This is a problem in the Hyper-V writer in Windows Server 2008.	To get the writer back to a stable state, restart the Hyper-V Virtual Machine Management service. Perform offline backups of the virtual machines to prevent the writer from going into a bad state.	Download and install KB959962 on the Hyper-V host to solve this problem.	We recommend that you deploy this update on all Hyper-V hosts protected by DPM.
Backup of Hyper-V virtual machine fails.	Daily backups failing. VSS, Hyper-V writer or DPM failures are seen for many virtual machines.	DPM allows 8 parallel backups per server. In certain environments, this may involve over 100 simultaneous backups.	Limit the number of parallel Hyper-V backups using the registry key `HKLM\Software\Microsoft\Microsoft Data Protection Manager\2.0\Configuration\MaxAllowedParallelBackups`. Under this key, create a DWORD - Microsoft Hyper-V. The value for the DWORD should be less than 8.		We recommend that you set the DWORD to 2.

Note
If the errors persist, review the event log on the target server and on the guest installation of the VM for which the backups failed for further troubleshooting. Please review errors with source=VSS.