OneDrive sync re-copies some files

[andrasgaal]

I have a sync relationship set up to backup my OneDrive to TrueNAS-SCALE-22.12.0. The configuration is PULL and SYNC without any special options. The job runs daily.

I have noticed that each and every run since weeks ago (not sure since when, this happens from the time logs are available) around 25GB worth of data is resynced. Total size of the OneDrive is ~500GB.

I am almost certain that this data did not change on the cloud copy, and the same data gets pulled again and again. See logs for two runs, from about 3 days apart:

While it's no biggie from a bandwidth perspective, any idea why content copied again and again? I am assuming the reason for copy is that it gets detected as changed on source, but why?

 

[Geopoliticus]

Are you sure the data isn't changed? Do you sync your photos to iCloud? I would check to see if something unanticipated is going on there. Depending on the number of devices and users (family) that might be syncing to your iCloud account I wouldn't be surprised if apple was doing something funny here.

 

[andrasgaal]

Yes, icloud photos are synced to OneDrive, and not a family icloud account. I am 99.999% that nothing modifies these files, OneDrive app on the phone does not report any changes and phone wifi traffic is also very low.
I meanwhile found a thread detailing a similar issue. Looks like this happens because of the way OneDrive reports file size (not matching with the local copy), and this makes it re-sync.