For the past eight month, Iâ€™ve been working with EMC and Microsoft to diagnose a problem. Several time a month, during the backup of our primary Windows 2008 R2 file server, all the VSS shadow copies get deleted for the volume containing all our shared departmental directories.
This has two major effects. First, it means that our clients no longer can recover files using the Previous Versions feature of Windows. Second, it casts significant doubt on the validity of the backups performed at that time, which EMC NetWorker reports as having completed successfully.
We have been unable to find a technical solution to the shadow copy loss, so we will be reconfiguring our storage and shared directories to accommodate the limitations of NetWorker. In the meantime, I want to note a few of resources that have been helpful in diagnosing problems with VSS (it will be easier to find them here than in my pile oâ€™ email):
Volume Shadow Copy Service (TechNet)
Volume Shadow Copy Service (MSDN)