NetWorker: Windows File System Backup for Azure Client is Missing Files

Summary: Windows file system on Azure skips files although there is no NetWorker directive to do so.

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Symptoms

Windows file system on Azure skips files although there is no NetWorker directive to do so.

Debug save output shows 
87713:save: Found prototype specification for '\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1288\': skip : hiberfil.sys
87713:save: Found prototype specification for '\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1288\Areas Compartidas\':+ skip : *.*

Cause

The backup file system is on Azure storage volume. The system uses Volume Shadow copy Service (VSS) Writer "Sync Share Service Writer." It skips files by design. 

To verify that this is the cause,

  1. Open a command prompt as Administrator and run: 
C:\>  DISKSHADOW /l writers.txt
DISKSHADOW> LIST WRITERS DETAILED
DISKSHADOW> exit
  1. Look at the output file for writers.txt. If you see the below message, then that confirms the issue.
* WRITER "Sync Share Service Writer"
.////
and that writer contains Components with affected drive 
            - Components:
            - File List: Path = J:\DataFiles, Filespec = *.*
            - Paths affected by this component:
                - J:\DataFiles
            - Volumes affected by this component:
                               - \\?\Volume{c34a534a-63a2-4aee-b47a-e2092dc7a901}\ [J:\]

Resolution

Turn off VSS for backing up Azure storage volumes with the command:

VSS:*=off

Windows client with VSS disabled

NOTE: Only do this for clients that backup file system data. Performing a backup without VSS makes it impossible to backup the windows DISASTER_RECOVERY:\ save set; meaning, Bare Metal Recovery (BMR) of the Windows VM would not be possible.

Affected Products

NetWorker

Products

NetWorker Family
Article Properties
Article Number: 000210906
Article Type: Solution
Last Modified: 04 Mar 2026
Version:  3
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