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Druva Documentation

VSS Basic Troubleshooting Guide

This article applies to:

  • OS: All windows OS post  WS 2003
  • Product edition: inSync Cloud/On-Premise/Phoenix


This article provides the basic steps to resolve VSS issues before you address error messages or resort to advanced troubleshooting.

Troubleshooting steps

  1. Check Windows event logs:

    Check both the application and system event logs for detailed VSS errors. Subsequently, also check the Hyper-V VMMS events.
  2. Check third-party backup software:

    Check for any third-party backup software. If found, uninstall it and reboot the server.
  3. Check Shadow Storage Space:
    1. Check the storage on each server with the below command.

      vssadmin resize shadowstorage /for=<drive letter> /On=<drive letter> /MaxSize=Values

      Reference: vssadmin resize shadowstorage

      Example:  vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=300MB
    2. If there is less shadow storage space allocated, increase the storage in accordance with the requirement or set it to unlimited.
    3. Delete any stale and old shadow copies using the following command:

      Vssadmin delete shadows /all
  4. Check Writers StatusVSS backups fail if application-specific writer, such as hyper-v writer or SQL, fails.
    Check the writer status with the following command:

    Vssadmin list writers
    The output must include all the writers listed and must be in a stable state.
  5. Troubleshoot unstable/failed writers using the common steps:
    • Check the service account of the corresponding writer. Ensure it is a system account.
    • Check the event log.
    • Check the service of the corresponding writer. List of some corresponding services mentioned below:
      • Hyper-V Virtual Machine Management
      • SQL Server VSS Writer
      • Oracle VSS writer
      • System Writer
    • Restart the concerned service and run the above command again.
  6. Advanced troubleshooting steps for unstable/failed writers.
    • Restart COM+ System Application Service
    • Restart Distributed Transaction Coordinator Service
    • Restart Volume Shadow Copy Service
    • Restart the corresponding VSS writer service. For example, Hyper-V VSS writer or SQL VSS writer
  7. Re-register all VSS & COM+ components.

    Run the following command using elevated command prompt.

    cd /d %windir%\system32
    Net stop vss
    Net stop swprv  
    regsvr32 ole32.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
    regsvr32 Vssapi.dll
    regsvr32 Vssui.dll  
    regsvr32.exe /i
    regsvr32.exe /i %windir%\system32\swprv.dll  
    regsvr32.exe %windir%\system32\vssui.dll  
    regsvr32.exe %windir%\SysWOW64\vss_ps.dll  
    regsvr32.exe %windir%\SysWOW64\msxml.dll  
    regsvr32.exe %windir%\SysWOW64\msxml2.dll
    regsvr32.exe %windir%\SysWOW64\msxml3.dll
    regsvr32.exe %windir%\SysWOW64\msxml4.dll
    regsvr32.exe %windir%\SysWOW64\ole32.dll  
    regsvr32.exe %windir%\SysWOW64\oleaut32.dll
    regsvr32.exe %windir%\SysWOW64\es.dll
    regsvr32.exe %windir%\SysWOW64\comsvcs.dll
    vssvc /register
    net start swprv
    net start vss
    net stop winmgmt  
    regsvr32 wmiutils.dll  
    net start winmgmt

  8. Multiple Providers
    • At the elevated command prompt, run the following command

      vssadmin list providers

    • The output must list one or maximum two providers as follows:

      • 'Microsoft Software Shadow Copy provider 1.0

      • Microsoft File Share Shadow Copy Provider

    • If there is any provider other than the above two, disable and stop the services corresponding to these providers. For example, the following providers.
      • Acronis VSS HW Provider
      • StorageCraft Volume Snapshot Software Provider
  9. To resolve any VSS-specific errors, use the solutions provided in the Troubleshooting VSS errors section.
  10. For advanced troubleshooting such as VSS trace, refer the Microsoft blogs: How VSS Tracing Works and Using Tracing Tools with VSS.