I have a hard drive that I am using syncthing via my Mac to sync to a raspberry pi at home. It all seems to be syncing but often when I take a peak, zero data is being transfered. If I pause and resume or restart then it starts transfering again.
Sometimes the hard drive is spinning and sometimes it is not.
Is it zero tranfer because it is compressing the data? Appreciate any advice.
Pausing, resuming and restarting Syncthing triggers an immediate full scan followed by a sync if necessary.
For efficiency reasons, when Syncthing is notified that a folder being watched has changed, Syncthing waits 10 seconds (the default) before scanning just in case additional notifications are queued up. File and directory deletes are a default 6x the change notification countdown timer (i.e., 60 seconds). So it might just be that you’re catching Syncthing during it’s regular pauses.
Also, like Windows and Linux, macOS makes use of file caching in memory so you won’t always see drive activity unless writes need to be flushed to disk and/or data needs to be loaded into cache.
A better method is to check out the Syncthing’s runtime log with optional debugging features if you’re curious about any sync activity (found in Syncthing’s web GUI under Actions → Logs).