Troubleshooting Volume Shadow Copy Service (VSS) Backups

1) Architecture and Packages

Ensure the correct backup client agent is installed for your architecture.

    Windows = 32 bits  /  Agent = 32 bits
    Windows = 64 bits  /  Agent = 64 bits

2) Disk Space

Ensure there is enough free disk space to host the volume snapshots.

3) Maximum Snapshot Volume

Ensure the snapshot maximum of 64 per volume has not been reached.

4) Windows Services

Agents use the Volume Shadow Copy Service (VSS) on Windows to back up open/locked files, perform image backups and backup applications and volumes via the VSS API. Under certain circumstances the VSS service fails to run properly so agents will not be able perform backups using the VSS API

In case of such errors please read carefully and follow the solutions given below to try and fix
the VSS service problem.

Ensure that VSS an other services are running and set to Automatic.

* Ensure that COM+ Event System is started
* Ensure that COM+ System Application is started
* Ensure that Remote Procedure Call (RPC) is started
* Ensure that System Event Notification is started
* Ensure that  MS Software Shadow Copy Provider is started
* Ensure that Volume Shadow Copy is started
* Reboot Windows after making these changes
* Start an Arkeia Backup to see if this resolves your issue

5) NT Backup

NT Backup uses the same VSS API as most backup product agents.
The internal Windows Shadow Copy Service DOES NOT use the external
VSS API and may be fully functional.

* Start an NT Backup to verify if can function in the environment.

6) Dell EqualLogic VSS Provider

Check the Windows Event Viewer for details when targeted to Dell EqualLogic Storage.

Dell EqualLogic has an option to provide Challenge Handshake Authentication Protocol (CHAP) initiator authentication and access control records to control which hosts (iSCSI initiators) can access a volume or snapshot (iSCSI target). It is also possible to configure the iSCSI access without a CHAP user.

* Check that a local CHAP user is setup in the Group Configuration under the iSCSI tab. 


* Check the VDS/VSS tab to confirm that a same CHAP user is set to allow VSS snapshots.

* If CHAP is not being used, allow the IP of the client in the VSS/VDS screen.

7) 3rd Party VSS Providers and Writers

Check to see if there are any non-standard providers that are causing the problem when performing the VSS snapshot.  If there are any non-standard providers listed, consider uninstalling them or contacting the Provider Vendor.  Uninstalling the faulty Writer or Provider will generally resolve the issue.

Use the following commands  list available VSS Providers and Writers.
If either command hangs, it is likely that a newly installed VSS provider is malfunctioning, which should be uninstalled.

    vssadmin list writers
    vssadmin list providers

* Uninstall any 3rd Party Backup Software or disable the Agent and it’s VSS options if not being utilized.

* In many cases, the uninstall will leave the VSS item in the list.
   For these cases, the item must be removed from the Windows Registry.

* Verify that each VSS service listed is actually started using Windows Services Controls.

* A listed VSS service which fails to start for some reason, can cause Windows VSS API problems.

* Check the Windows event logs for VSS Errors

              Type: Error
              Source: VSS

Listed 3rd party VSS Services must be running and fully functional:
    * Service is running
    * Still installed

The service “Data ONTAP VSS Hardware Provider” was not running and not able to start because of wrong user credentials. Updating the user and password for the service allowed the services to start successfully and resolved the VSS API issue.

8) Windows Application Services

Ensure that your Windows Application VSS Services are started

* Exchange
* Sharepoint
* SQL Server
* etc…

9) Windows Updates

Check to see if you have the latest Windows updates & patches installed by clicking:

    Start–>Windows Update

If you are using Windows 2003 there is a VSS update package available that is required to be installed in order to have open files backup support on Windows 2003:

Start an Arkeia Backup to see if this resolves your issue

10) VSS SDK and Shadow.exe

Although the Windows Environment can create a Shadow Copy, it’s very possible
that the VSS API is blocked.

To determine if the problem with the VSS provider exists outside of Arkeia, use the MS-provided utility called “vshadow.exe”, which calls the  MS VSS API to check if it can access the VSS writers, just like Arkeia or any other backup application. The ‘VSHADOW.EXE’ utility is part of the Volume Shadow Copy Service, available within the MS Windows Software Development Kit (SDK), which can be downloaded from the Microsoft support website; such as:

There are various versions of this tool for Windows/XP, Windows/2003, and Vista.
The VSS SDK install uses a directory like this, by default:

    C:\Program Files\Microsoft\VSSSDK72\TestApps\VShadow\bin<br>
Run this utility from a MS-DOS prompt.
Here is the syntax, assuming ‘C:’ is the OS drive letter:

    vshadow  -nw  C:   >vss_nw.out
    vshadow  -p   C:   >vss_p.out
    vshadow  -wm2      >vshadow_wm2.out
    vshadow  -ws       >vshadow_ws.out

If “vshadow.exe” fails with the same error message, then you have a deeper problem with your Windows Environment.

11) Re-register VSC Writers and Providers

List VSS Writers:

    vssadmin list writers

This should output a list of writers and their status. They should all be reported as stable (you may need to scroll up to see the entire list). If some aren’t listed as stable then there is a problem with your Windows installation and you will need to re-register the VSC dll’s.

    vssadmin list providers

It should list at least one item (MS Software Shadow Copy provider). If none are listed then there is a problem with your Windows installation and you need to re-register the VSC providers.

To re-register VSC dll’s and providers, follow these instructions:

    Got to C:\WINDOWS\System32 and run the following commands (sequential):

        Net stop vss
        Net stop swprv
        regsvr32 ole32.dll
        regsvr32 oleaut32.dll
        regsvr32 vss_ps.dll
        Vssvc /Register
        regsvr32 /i swprv.dll
        regsvr32 /i eventcls.dll
        regsvr32 es.dll
        regsvr32 stdprov.dll
        regsvr32 vssui.dll
        regsvr32 msxml.dll
        regsvr32 msxml3.dll
        regsvr32 msxml4.dll

Reboot your computer and type the commands list writers/list providers again - if everything is
ok all your writers/providers should be displayed w/o errors.

12) How to clean up a damaged COM+ catalog

The COM+ catalog is a catalog of all the available COM+ applications, classes and attributes on
a given system. If the catalog becomes damaged, programs that rely on COM+ won’t work
properly. One example of such a service that depends on COM+ is the Volume Shadow Copy

For more information you can relate to this Microsoft support knowledge base article:;en-us;315296

13) Corrupted data on the drive

Corrupted data on the drives can also cause VSS_VETO errors.
Run CHKDSK on each drive with the /f switch to fix any errors on the disk.

14) Too Many Snapshot Requests

In rare cases, too many snapshot requests can cause the VSS Writers to fault.
Attempting to backup a single VSS object such as the C: Drive by itself will


Hope this bit of information helps the Community :)

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Nice, thanks for sharing the knowledge.