just set up a new server which will replace my old one…
I scp’d the files from the old to the new server and defined my master desktop device as “master” (because it is).
although all files on the old server were “in sync” my master desktop device shows, that all files are out of sync (although they exist on the new device)
my question to this: why do the files on the new server seem to be out of sync?
the icons on my master desktop device in front of the “out of sync” files are arrows-down that are suggesting, that these files should be downloaded to the master although the override button icon shows the other way: arrows-up…
Because they have a different history from Syncthing’s point of view, which needs to be reconciled. If there are no differences, no changes will be made.
The out of sync icon (“download”) indicates what would happen. That doesn’t happen right now, because it being master prevents it from doing any downloads. The “override” button will instead force out the master’s version to everyone else, hence the “upload” indicator.
but what would happen, if the desktop would not be master / what could be the differences between the files? maybe the date?
To clarify this… Syncthing uses version vectors to describe a file’s history. Somewhat simplified, these contain information similar to “this file was first found on device A, then modified on device B, then modified on device C” and allows Syncthing to determine if one version of a file is newer than another one or if they are in conflict.
Once that has been determined Syncthing will figure out what (if anything) is needed to bring a file into sync - maybe just update the timestamp or permissions, maybe pull a few new blocks, maybe do nothing at all.
In your case, it sounds like for each of the files you have two different versions - one like “created on device A, modified on device B” and another now tagged as “created on device C”. These are in conflict since they share no history, but apparently share a name.
Syncthing will do the conflict resolution (unless prevented from doing that by being “master”), then notice that the files don’t actually differ, and create a common version vector / history for all of them.