How can I check if USN and VSS are working?


I installed Duplicati as a server on a Window 10 machine and set both usn-policy and snapshot-policy to on in the GUI.

I also added the options as arguments to the command line of the service definition, in case they must be passed to the server at startup, so now the ImagePath entry in the registry for this service is:

“C:\Program Files\Duplicati 2\Duplicati.WindowsService.exe” --snapshot-policy=on --usn-policy=on

After that I restarted the service and performed a backup.

The problem is that I checked in the backup db and the ChangeJournalData table is empty, so USN does not seem to be working, but haven’t got any warning. Also, I have no idea how to check if VSS is being used.

Any suggestion? Thanks a lot.


Welcome to the forum!

If you have the policy options set to “On” then you’ll get a warning if either doesn’t work. You don’t have to put it on the command line of the service - setting these options in either the global settings or job-specific settings is sufficient.

Actually I just tested this. It seems with USN set to “On” it results in a job failure if USN journal can’t be accessed. It’s supposed to result in a job warning if set to “On” and a failure if set to “Required.”

In any case, if you see no warnings or failures at all, I would say they are working for you.

Correction - the job completes but it generates a red error dialog. I believe the correct behavior is for it to generate a warning message. Also, I discovered that when the snapshot policy is set to Auto, no informational entry is added to the log if the snapshot fails.

I have submitted PR #4085 to correct both issues.

Thank you Rod! I really appreciate your help.

Incidentally, today I deleted a backup, re-run it, and now the ChangeJournalData table is populated. I must have done something wrong, yesterday.