Functionality and dependency of VSS (Volume Shadow Copy Service) in Backup Exec and System Recovery

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Various VSS errors in a very wide range of resources.


Numerous backup jobs run by Backup Exec or System Recovery are dependent on Microsoft’s Volume Shadow Copy Service, (VSS). VSS is used to create snapshots of data that is to be backed up. VSS was introduced with Windows XP and Server 2003. The following backup jobs use VSS:

1. All System State backups of Windows Server 2003 and higher systems.
2. All Shadow Copy Component backups of Windows Server 2003 and higher systems.
3. All File backups using Advanced Open File Option (AOFO) of Windows Server 2003 and higher systems
4. All File backups of Windows 2008 and higher, (With or without AOFO enabled in the job)
5. All backups of Microsoft Exchange 2007 and above.
6. Backups of Microsoft Exchange 2003 that have AOFO selected in the job (Not recommended)
7. Backups of Microsoft SQL that have AOFO selected in the job (Not recommended)
8. Backups of Microsoft SharePoint that have AOFO selected in the job (Not recommended)
9. Backups of Microsoft Hyper-V Virtual Machines
10. GRT functionality of the VMware Agent

Backup Exec and System Recovery act as VSS requestor in the snapshot process.

For more information about the components used to make a VSS snapshot:

The first step in troubleshooting any snapshot error is to determine what is being backed up. To clarify the issue, determine the following:

  • What resource is being backed up?
  • Where does the resource reside?
  • When does the backup happen?
  • Once this has been established you can proceed to the event viewer of the problem system to collect more information.

VSS Writer Errors

To check Writer Status in a command prompt type  vssadmin list writers

To check to see if there are any other VSS providers installed on the server run vssadmin list providers at the command prompt.

How to enable/disable Backup Exec verbose debug logging

Common Articles Tech Notes

Microsoft VSS Fixes and Updates:
Windows Server 2003:

Windows Server 2008 and SP2:

VSS Diagnostics

System State or Shadow Copy Component backup fails with VSS snapshot error.

Error message when you run the "vssadmin list writers" command on a Windows Server 2003-based computer: "Error: 0x8000FFFF"

How to troubleshoot "AOFO: Initialization failure" errors for "Microsoft Volume Shadow Copy Service (VSS)" service during Backups/Restores

Additional troubleshooting steps for Microsoft VSS errors when backing up Exchange 2007 database.

Backups appear to hang when attempting to create a Snapshot using VSS (Volume Shadow Copy Service)

An unexpected error occurred when cleaning up snapshot volumes. Confirm that all snapped volumes are correctly resynchronized with the original volumes.

0xe000959b, VMware is unable to create a snapshot due to the freeze or thaw script used for preparing the guest operating system for the snapshot is not called correctly from VMware.

Important This article is not for use with Windows Vista, with Windows Server 2008, or with later Windows operating systems. Starting with Windows Vista and with Windows Server 2008, Windows component installation is manifest-based. Trying to manually register specific components, as described in the following steps, can have unexpected results that may require Windows be reinstalled to resolve.

Don’t reregister dll’s on Windows 2008 or 2008 R2:
Beginning with Windows Vista and Windows Server 2008, Windows component installation is manifest based, and most of the registry is locked down even to Administrator. However, the VSS binaries in Windows Vista and Windows Server 2008 still contain the code to perform self-registration. The code is removed in Windows 7 and 2008 R2.  It is not recommended to Re-register VSS binaries in Windows Vista and Windows Server 2008 or later operating systems.  For more information please contact Microsoft, or refer to their documentation.




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