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Exchange logs not being truncated

KB ID: 1878
Product: Veeam Backup & Replication
Version: 6.x, 7.x, 8.x
Published: 2014-04-21
Last Modified: 2020-08-13


This KB provides information on items to check when logs are not being truncated, even when Veeam Backup & Replication is stating that everything is successful.


There are various causes for failure of truncation operations, both in the Veeam Backup & Replication application, and within the Exchange Windows guest itself.


Make sure that the job is set to use Application-Aware Image Processing and proper credentials are being used:

User-added image

You will then want to check to make sure that transaction logs are set to be truncated on successful backup:

User-added image

If this is set correctly, make sure that the command is being sent to the Exchange server. You can verify this by analyzing the VeeamVSSSupport.log
(VeeamGuestHelper.log in VBR v8+) file that can be found in the following location:
  • Windows 7/8 Generations: C:\ProgramData\Veeam\Backup
  • Windows XP/2k3: %allusersprofile%\Application Data\Veeam\Backup
If the command is being sent, you should see the following in the log file:
INFO                Processing external FinishSnapshot command.
                         Notifying writers about the 'BACKUP FINISH' event.
                         Truncate logs: [true].
                         Processing external FinishSnapshotEX command, job id ‘{job ID}’, is logs truncation enabled yes.. ok.
If this is being sent, we will want to look at Windows event logs for any possible errors as well as the VSS writers.
Run the following in an elevated CMD prompt and verify the Exchange writer is present:

vssadmin list writers
If the writer is not being listed or is in a failed state, the Exchange server should be rebooted, then it should be verified that the writer returns and shows as Stable/No Error. Once this has been done, retry the Veeam job and verify log truncation.
Within the event logs, look for any Exchange based errors. If the Exchange configuration is utilizing Distributed Availability Groups (DAG), the replication process between the different nodes can prevent log truncation if there are any errors. These will show with the event source MSExchangeRepl. If there are errors here, generally these are not affected by Veeam Backup & Replication processes and should be addressed in the Exchange and/or Windows configuration. To isolate whether the issue is caused within 
Veeam Backup & Replication processes or within VSS itself, enabling the Windows Backup role on the server and running a native Windows Backup (system state) will generally isolate the issue to the operating system.

More information

To manually test shadow creation and truncation please review KB1980: Using the Diskshadow Utility to manually test VSS operations.

Information on Application-Aware Processing and Log Truncation:
MSExchangeRepl errors:

KB ID: 1878
Product: Veeam Backup & Replication
Version: 6.x, 7.x, 8.x
Published: 2014-04-21
Last Modified: 2020-08-13

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