First of all thank you for making such fantastic product open source!
Recently came to face following scenario. I have two remote computers, which already have data synchronized by external means (example BTsync or HDD shipped by FedEx). It’s an untouched archive 100% identical on both end. Has about 100.000 files.
I have added it as a folder to sync on machine A then when shared with machine B selected the folder with existing data.
It looks like Syncthing started synchronizing files before it finished scanning. In the process it has deleted about half of the files and it’s synchronizing them over internet, which I don’t want because they were already there.
I also tried the same with adding folder on machine A, waiting for scan to finish and then sharing / adding folder on machine B. Same thing happen.
The question is, what is the correct procedure for establishing a sync on data that is already “pre-synchronized”?
If the files were 100% in sync before you set up syncthing, then it may look like syncthing is transferring files while it actually is not. In an initial sync it sure as hell shouldn’t delete any files, because that wouldn’t make sense. Are you sure this is happening, i e can you actually see it in the folders or is that just the way you interpret the gui?
If the folders were not in sync but share mostly the same data with one folder being more recent, read this thread from 4 days ago