Diagnosing and resolving VSS-related issues (4037005)

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Title

Diagnosing and resolving VSS-related issues
Description

This article serves as a guide for diagnosing and troubleshooting VSS related issues for those NetVault Plugins that use the Microsoft Volume Shadow Copy tools.
Cause

When a VSS-backup job is executed, the plug-in might generate one or more shadow copies (snapshots). After completing the job, the plug-in sends the VSS subsystem a notification indicating that the shadow copy can be deleted. Additionally, if the VSS job is aborted for any reason and the plug-in detects the event, the plug-in sends the same type of notice. However, there are instances in which shadow copies are not deleted, which means that the VSS inadvertently stores obsolete shadow copies.
If you determine that the plug-in is unable to create a VSS shadow copy, or if the backup job fails during the processing of taking or managing snapshots, it might indicate that obsolete shadow copies are interfering with the VSS subsystem.

Resolution

In addition to the NetVault Backup logs and the individual job logs, the following resources can expedite the diagnoses of VSS-related issues with backup and restore jobs.

•	Windows Application Log – In this log, VSS Writers record detailed error messages that are not logged in the NetVault Backup logs. For more information, refer to Windows Application Log athttp://msdn.microsoft.com/en-us/library/ms157312.aspx.

•

Vssadmin and DiskShadow – You can use Vssadmin to list the VSS writers and providers, display their current status, and ensure that the VSS Writers that the plug-in depends on are enabled and available for use. Vssadmin also indicates whether it has encountered any errors. DiskShadow, which is a newer utility, also provides information that might be useful. For more information, refer tohttp://technet.microsoft.com/en-us/library/bb491031.aspx and http://technet.microsoft.com/en-us/library/cc772172(v=WS.10).aspx.

You can also obtain additional information from a command prompt by typing vssadmin or diskshadow.

Technical Support recommends that you use the Vssadmin and DiskShadow utilities to maintain the VSS subsystem, as well as to address specific issues, such as deleting obsolete shadow copies. You can use these utilities to list the shadow copies stored by the VSS, to remove shadow copies, and to manage the space allocated in a specific volume for the storage of shadow copies.