Dell NetWorker 19.9 Administration Guide

VSS backups fail if a critical volume is offline during the backup operation. You can remedy the problem by following the steps that are outlined in the Microsoft Knowledgebase (KB) article 980794, which can be found at:

http://support.microsoft.com/kb/980794

The patch that is mentioned in this knowledgebase article is most likely on the Windows system if it is up-to-date. In this case, you can create and populate the Registry keys as described in the article.

This issue is most often encountered when backing up a passive node in an MSCS cluster and a critical volume is not on the physical host of the passive node but is instead on the physical host of the active node.