# USN option working inconsistently

**URL:** https://forum.duplicati.com/t/usn-option-working-inconsistently/9224
**Category:** Support
**Created:** [February 18, 2020, 1:58pm UTC](https://forum.duplicati.com/t/usn-option-working-inconsistently/9224 "2020-02-18T13:58:00Z")
**Posts on this page:** 1
**Showing post:** 6

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### Author: ![ts678](https://forum.duplicati.com/letter_avatar_proxy/v4/letter/t/8491ac/32.png) [@ts678](https://forum.duplicati.com/u/ts678)
#### Post date: [February 19, 2020, 12:55pm UTC](https://forum.duplicati.com/t/usn-option-working-inconsistently/9224/6 "2020-02-19T12:55:31Z")

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> [@anon91846751](#):
>
> It is not a USN failure.

It’s not a hard failure that will cause --usn-policy=required to error. There are a few soft failures that can cause full scans to happen. You can see them in the log at Information level. An example of such log is:

> 2020-02-19 06:38:16 -05 - [Information-Duplicati.Library.Main.Operation.BackupHandler-SkipUsnForVolume]: Performing full scan for volume "C:"

and possibly this case is:

> <https://github.com/duplicati/duplicati/blob/082a14fc22efdef226c1bee956f85009f7104fb3/Duplicati/Library/Snapshots/UsnJournalService.cs#L67-L68>

> [@anon91846751](#):
>
> as long as the ChangeJournalData table is empty

Then the question someone can look at is how it managed to stay empty despite post-backup work at:

> <https://github.com/duplicati/duplicati/blob/082a14fc22efdef226c1bee956f85009f7104fb3/Duplicati/Library/Main/Operation/BackupHandler.cs#L233-L245>

I’d _like_ to find a way to tie this into your [P.S.](https://forum.duplicati.com/t/usn-option-working-inconsistently/9224) issue on repeating opens, but I can’t explain 30% reopens:

[Duplicati detects spurious timestamp changes](https://forum.duplicati.com/t/duplicati-detects-spurious-timestamp-changes/9225)

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