NetWorker: Error 'Failed to get writers list for WINDOWS ROLES AND FEATURES' is Visible After Custom Provided 0-Byte Writerlist.txt File

Summary: The custom provided 0-bytes length writerlist.txt file makes the writers validation steps fail in preparation of Volume Snapshot Service (VSS) backup.

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Symptoms

A user is experiencing a VSS backup error on one node in a cluster. While the other node is always successful, the problematic resource fails with the following error message: 
11/16/17 17:42:37.343548 WINDOWS ROLES AND FEATURES: sow_init_save_sysset_walker () called 11/16/17 17:42:37.343548 WINDOWS ROLES AND FEATURES: sow_save: Failed to get writers list for WINDOWS ROLES AND FEATURES: WINDOWS ROLES AND FEATURES: ERROR: Failed to get writers list for WINDOWS ROLES AND FEATURES: 95088:save: Cannot back up the volume save set because the initialization of VSS did not succeed.
This indicates a situation where VSS writers are not recognized correctly, thus preventing the VSS operation to finish.

The error is reproduced both with scheduled backup policies and running the save command.

Cause

Execution of the save command on both the nodes hosts is necessary to reproduce the error and allows a side-by-side comparison of the generated logs: 
C:\Program Files\EMC NetWorker\nsr\bin>save -D9 -s myserver -b Datadomain -o "VSS:NSR_SYS_WRITER_WIN32_SERVCOMP_USER=yes" C:\Lgto\nmsap91_win_x64\win_x64\networkr\file_to_backup
The two logs are in synch until the below method is triggered: 
PopulateSupportedWriterList() Enter
After this point, both the nodes show the: 
CVssSysReqBackup::Init(): Successfully updated writer list.
Then both nodes start the writers validation steps with the method: 
IsWriterSupported()
This is where the difference begins:
  • NODE ONE:
IsWriterSupported() Enter.
04/10/18 11:22:57.671021 VSS Writer {d61d61c8-d73a-4eee-8cdd-f6f9786b7xxx} is supported
04/10/18 11:22:57.671021 IsWriterSupported() Exit
[for each writer]
  • NODE TWO:
IsWriterSupported() Enter.
04/10/18 11:14:17.601823 VSS Writer {d61d61c8-d73a-4eee-8cdd-f6f9786b7xxx} is not supported
04/10/18 11:14:17.601823 IsWriterSupported() Exit
[for each writer]
At the end, the following is received in NODE TWO: 
95088:save: Cannot back up the volume save set because the initialization of VSS did not succeed
In NODE ONE, the debug log shows that during the execution of the method, the default supported system writer list is used: 
 PopulateSupportedWriterList() 
04/10/18 11:22:56.702238 PopulateSupportedWriterList() Enter./n04/10/18 11:22:56.702238 lgwstat: Failed to open file/directory: \\?\C:\Program Files\EMC NetWorker\nsr\bin\writerlist.txt
04/10/18 11:22:56.702238 PopulateDefaultSupportedWriterList() Enter.
04/10/18 11:22:56.702238 PopulateDefaultSupportedWriterList() Exit
But in NODE TWO, it seems that the below is completed and used: 
PopulateUserSupportedWriterList()
Instead of the: 
PopulateDefaultSupportedWriterList().
04/10/18 11:14:16.664317 PopulateSupportedWriterList() Enter.
04/10/18 11:14:16.664317 PopulateUserSupportedWriterList() Enter.
04/10/18 11:14:16.664317 PopulateUserSupportedWriterList() Exit
Upon a check in the client file system NODE TWO, we find that there is a user-provided writer list which is a 0-byte file: 
C:\Program Files\EMC NetWorker\nsr\bin>dir writerlist.txt
Volume in drive C has no label.
Volume Serial Number is 5F41-F8xx
Directory of C:\Program Files\EMC NetWorker\nsr\bin
11/10/2017  10:01 AM                 0 writerlist.txt
1 File(s)              0 bytes
0 Dir(s)  33,237,905,408 bytes free
That is used to populate the writer list during the execution of the method: 
 PopulateUserSupportedWriterList()
Being a 0-bytes file which contains nothing, the 
PopulateUserSupportedWriterList() 
Cannot create a consistent data structure for the writers which are then set as not supported.

Resolution

Removal of the 0-byte file from NODE TWO file system is necessary. 
C:\Program Files\EMC NetWorker\nsr\bin\writerlist.txt
When using the: 
PopulateDefaultSupportedWriterList()
Allows the completion of the save operation.

Once the removal is done:
  • NODE TWO:
PopulateSupportedWriterList() Enter./n04/11/18 14:31:10.389231 lgwstat: Failed to open file/directory: \\?\C:\Program Files\EMC NetWorker\nsr\bin\writerlist.txt04/11/18 14:31:10.389231 PopulateDefaultSupportedWriterList() Enter.
04/11/18 14:31:10.389231 PopulateDefaultSupportedWriterList() Exit.
04/11/18 14:31:10.389231 PopulateSupportedWriterList() Exit.

Like what we see on NODE ONE. The VSS backups are now possible with NODE TWO.

Affected Products

NetWorker Family, NetWorker, NetWorker Series
Article Properties
Article Number: 000056703
Article Type: Solution
Last Modified: 29 Jul 2025
Version:  4
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