I've been backing up Hyper V VM's for a while using DISKSHADOW (for testing purposes). For the most part it works great, but every now and then I run into a Hyper V Host that just, for no apparent reason, starts hanging when running DISKSHADOW. It doesn't matter if I run DISKSHADOW interactively or in script mode, once I issue the CREATE command, it just hangs. What's worse, once it starts hanging, it seems to continue hanging on each subsequent attempt. On some occasions a restart has cleared up the issue, but I have actually had to move VMs I want to backup to other hosts because the problem persists.
The Hyper V Hosts having the issues are Windows Server 2008 DataCenter Service Pack 2 (Build 6002). No issues with R2... yet.
Here is the script I use:
reset
Delete Shadows All
set Context Persistent
Begin Backup
Writer Verify {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}
Add Volume C: ALIAS system
Add Volume \\?\Volume{d67d17e8-90be-11de-9f37-0023aef8c36e}\ ALIAS NUMBER0
Add Volume \\?\Volume{d551c1d1-9233-11de-9f37-0023aef8c36e}\ ALIAS NUMBER1
Add Volume \\?\Volume{d551c244-9233-11de-9f37-0023aef8c36e}\ ALIAS NUMBER2
Add Volume \\?\Volume{d551c2b7-9233-11de-9f37-0023aef8c36e}\ ALIAS NUMBER3
Add Volume \\?\Volume{d551cf67-9233-11de-9f37-0023aef8c36e}\ ALIAS NUMBER4
Add Volume \\?\Volume{72206281-93a0-11de-9f37-0023aef8c36e}\ ALIAS NUMBER5
Add Volume \\?\Volume{722063dd-93a0-11de-9f37-0023aef8c36e}\ ALIAS NUMBER6
Add Volume \\?\Volume{09916734-9c56-11de-9f37-0023aef8c36e}\ ALIAS NUMBER7
Add Volume \\?\Volume{099167a7-9c56-11de-9f37-0023aef8c36e}\ ALIAS NUMBER8
Add Volume \\?\Volume{b4d88841-a998-11de-9f37-0023aef8c36e}\ ALIAS NUMBER9
Create
end Backup
Expose %NUMBER0% F:
Exec c:\HVVMBackupWorker\swap\CopyVHD_NUMBER0.CMD
Unexpose F:
Expose %NUMBER6% F:
Exec c:\HVVMBackupWorker\swap\CopyVHD_NUMBER6.CMD
Unexpose F:
Expose %NUMBER9% F:
Exec c:\HVVMBackupWorker\swap\CopyVHD_NUMBER9.CMD
Unexpose F:
Exit
Again, this script has worked on this server numerous times in the past.
The most frustrating part of this is that there is no identifiable difference in the number or type of events logged in the Windows Event Logs when the process works and when it hangs.
So here are my questions:
1. Does VSS create any logs outside of Event logs?
2. Is there any other way to query the VSS service for possible errors?