Microsoft Hyper-V VSS Writer Issues

[guest]

I'm running Server 2008 with Hyper-V.

I have a simple script that uses diskshadow to utilize VSS to copy my virtual machines to a NAS device:

echo Delete Shadows Volume C:\ > Script.dsh
echo Set Context Persistent >> Script.dsh
echo Begin Backup >> Script.dsh
echo Writer Verify {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de} >> Script.dsh
echo Add Volume C:\ ALIAS MyShadow >> Script.dsh
echo Create >> Script.dsh
echo End Backup >> Script.dsh
echo Expose %%MyShadow%% X: >> Script.dsh
echo Exec CopyVM.CMD >> Script.dsh
echo Unexpose X: >> Script.dsh
echo Exit >> Script.dsh
echo MD "\\192.168.1.14\backups\MYSERVER\MONDAY\Volume{148e48a7-543a-11dd-b6ed-806e6f6e6963}\" > CopyVM.CMD
echo MD \\192.168.1.14\backups\MYSERVER\MONDAY\Volume{148e48a7-543a-11dd-b6ed-806e6f6e6963}\Virtual Machines\MYVIRTUALSERVER >> copyVM.CMD
echo COPY "X:\Virtual Machines\MYVIRTUALSERVER\MYVIRTUALSERVER.vhd" "\\192.168.1.14\backups\MYSERVER\MONDAY\Volume{148e48a7-543a-11dd-b6ed-806e6f6e6963}\Virtual Machines\MYVIRTUALSERVER\MYVIRTUALSERVER.vhd" >> CopyVM.Cmd
DiskShadow /s Script.dsh
Exit

When i tested this on the server, it worked fine. It created the shadow, exposed it, copied it to my NAS and finished.

I added the job to scheduled tasks and set it to run in the evening. For some reason, it failed with the following errors in my event log:

App: E 'Mon Aug 04 20:12:33 2008': VSS - " An unhandled exception was encountered while processing a VSS writer event callback. The VSS writer infrastructure is in an unstable state. The writer hosting
process must be restarted in order to resume VSS functionality. Writer name: Microsoft
Hyper-V VSS Writer Writer id: {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de} Writer instance:
{ffee4b9e-2efa-4e65-b1ba-f90a2766b0d9} Process command line: C:_Windows_system32_vmms.exe
Process ID: 1788 Writer operation: 1013 Writer state: 4 Exception
code: 0xe06d7363 Exception location: 02 "

Sys: E 'Mon Aug 04 20:12:28 2008': PlugPlayManager - " The device 'Msft Virtual Disk SCSI Disk Device'
(SCSI_Disk_Ven_Msft_Prod_Virtual_Disk_2_9a9c854_0_000000) disappeared from the system without first being prepared for removal. "
Sys: E 'Mon Aug 04 20:12:28 2008': PlugPlayManager - " The device 'Storage miniport driver' (VMBUS_{9e7cea05-51c7-4d9f-815f-9c19b87c62ce}_1_3189fc23_0_{9e7cea05-51c7-4d9f-815f-9c19b87c62ce})
disappeared from the system without first being prepared for removal. "
Sys: E 'Mon Aug 04 20:12:24 2008': volsnap - " The shadow copies of volume __?_Volume{e4435086-5ff7-11dd-a59d-00188b426d49}
were aborted because the shadow copy storage volume was not present. "


I did some googling, but nothing specific comes up for any of these errors on Server 2008 or Hyper-v.

I did go into diskshadow and noticed that my Writer for Hyper-V did indeed dissapear (as indicated by the error message). I restarted Hyper-V Virtual Machine management and was able to manually fire off the backup with no issue.

Anyone have any thoughts on what happened during my backups? I'm trying to stabilize the process until another backup solution is available that can do this process for me.

[guest]

Do you mean that, after the failure, you see the error "The VSS writer infrastructure is in an unstable state" in the Event Viewer and then the Hyper-V writer doesn't show up in the output of "vssadmin list writers"?



Well, this seems a known issue and is being investigated. We have seen this error if some broken symbolic links presented due to unplanned failure.



The hotfix is in work and some tests are still needed. For now, I am sorry to say that there is no workaround for it and I am sorry if this brings any inconvenience.



Thank you for your understanding.



Best regards,
Chang Yin