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Title
VSS Timeout in Event Log -
Description
On the Core, the error will display as: "VSS subsystem error". Volsnap fails first, trying to create a VSS snapshot for a very busy volume, then VSS fails resulting in the AppAssure backup displaying the "VSS subsystem error".On the agent - it's this: http://technet.microsoft.com/en-us/library/cc734267%28v=WS.10%29.aspx - It may include the text "The flush and hold writes operation on volume %2 timed out while waiting for file system cleanup."Note: This is an error message from the Event Log, not from AppAssure.
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Cause
The IdleTimeout registry value specifies the amount of time, in seconds, that the VSS service will wait when it is idle. If this timeout value is reached and there are no tasks for it to perform, the VSS service will shut down.
This registry value can be found under the following registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VSS\Settings
If this registry value does not exist:
The actual timeout value that is used is 180 seconds (3 minutes) by default.
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Resolution
WORKAROUND:
You can create a value with the name IdleTimeout and the type DWORD and set it to the desired value.
If this registry value is set to 0 seconds:
The actual timeout value that is used is 180 seconds (3 minutes).
If you set this registry value:
VSS uses the timeout value that you set.
You can specify any value between 1 and FFFFFFFF seconds. However, it is recommended that you choose a value between 1 and 180 seconds.
Windows Server 2003 and Windows XP: This registry key is not supported.
For Additional info, see: http://msdn.microsoft.com/en-us/library/windows/desktop/bb891959(v=vs.85).aspx
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Additional Information
In the specific case where this was discovers: There are 150+ users working with file shares on that machine. LOTS of open files with a lot of data in volume's "write cache". when VSS creates a new snap, all that data from cache should be flushed to disk, however, there is not enough time to do this -> Volsnap fails, VSS snap isn't created > backup fails =) The solution being explored is either disabling write-caching for the volume or moving Shadow Storage to a different volume, which is not on the same iSCSI SAN. It doesn't look that there is a timeout for Volsnap. and the IdleTimeout from the SOL is most likely has nothing to do with it.