Hi there,
I am running a NC 21.0.2 instance on a VPS (CentOS 8) and in addition make use of Group Folders 9.0.2 to share project files with other people involved in a project we are working on.
When first time syncing with my local computer, I had to create the upmost level of the folder structure of this project on my local computer inside the group folder settings in the NC instance.
Afterwards I set up the NC client (3.2.2git (build 5901) for Mac on my machine and the contents of my local machine was synced with the group folders on the NC instance on the VPS. (No longer hundred percent sure about the chronological order of this procedure, since I did it half a year ago.)
This means, that now in my local project Folder and in the NC project instance the contents getās synced flawlessly at any time.
For some reason I had to reinstall my local OS. After the install I went on working with the project and added several files in my local project directory but I had not yet setup the NC client sync again.
When I now try to set up the NC client sync again - this client takes the NC VPS instance as the source and my local machine as the target and I donāt see an option to tell the client, that it should handle this differently.
Did I oversee sth? Is there a way to tell the client, which is source and which is target?
Any help is highly appreciated -
Thanks in advance,
Hubertus
NC syncing is akin peer-to-peer as opposed to client-server you treat it.
With syncing the only variable that matters is the time stamp.
The file having the latest time stamp gets copied and overwrites all other versionsā¦
It does NOT matter where this file was created/edited - locally or on the NC server sideā¦
1 Like
Thanks a lot for your very helpful information concerning the way NC handles and syncs the files which helps me understand the concept better.
At the moment I had to make a cleaninstall of my local OS (macOS 10.14.6).
Then I copied my homedirectory back onto the machine from the backup.
One directory inside there is the one, which I sync with NC.
Having a lot to do, I go on working on my projects and donāt set up the NC sync immediately after reinstall.
Means, there are some changes/newer files in my local NC-directory.
When I then later want to set up my local NC-Client again and inside the setup process the client asks for the local directory to sync with and I choose that local project directory - the client refuses and says, that this directory is not empty ā¦
This means, I first have to make a new empty project directory, let the files from the NC instance on the VPS āsyncā back to my local drive in that empty folder, pause the sync VPS <> local drive in the NC-client and than in a second step have to make another local sync with the two project directories ā¦
And that is quite a bit complicated and like scratching with the right hand on the left ear ā¦
I understood, that the peer-to-peer syncing works different.
Or is there a better way to get this sync working again?
Any help is highly appreciated!
Thatās correct.
It is common senseā¦
It thinks you selected the folder by mistake: it serves different purposes since it has files insideā¦
So, instead of running the risk to overwrite files or prompt you every time it runs into the same filename, it simply refuses to sync to non-empty foldersā¦
I donāt think soā¦
1 Like
@anon71540698 ā¦ thanks again for taking your time to answer me 
I think my āwishes/expectationsā concerning NC sync have a lot to do with other concepts of backup software - like you mentioned earlier > client - server and evenmore the ability inside these applications to decide between copy, sync, one-way, both-ways etc. ā¦
NC has a lot of wonderful options and features, which I will not cease to use bec. of a sync-behavior, which I would prefer different
But thanks to your friendly help I have an answer to my questions and can let things go concerning this subject. - So here are three kudos for you ā¦ 
It is not really a backup, just like RAID1 is not backupā¦
Backup is a snapshot in time you can always go back to.
Sync (and RAID1) is just another real-time copy, insurance against hardware failureā¦
If you delete a file - itās gone. On both copiesā¦(!)
Unless you start playing with turning sync on for particular times, etc. Not a good ideaā¦
wow, yes, that brings it absolutly clear to the point -
The comparison between RAID1 / Sync on the one side and backup on the other side -
When starting to use NC I had understood very quickly, that deleting a file accidentally here or there ā¦ means it immediately is lost in space, unless you donāt have a (or even better two) additional (incremental) backups ā¦
Thanks again!
Well there actually is a trashban feature. So if overwriting files, they can still be recovered.
I would if I where you, instead have choosen an empty temporary folder on you local machine. Then I would copy that one using the NC web interface to an NC location not synced.
Then I would have created a new sync point to the āoldā folder mapped to a temporary NC folder. Remember to have the checksum app or feature activated and make sure it is configured to always make a checksum.
When done syncing, merge the two folders using the NC web interface and ignore identical files and overwrite with newer versions for those with newer versions. When all done and all files are in the desired versions or state: Cleanup and make sure the desired files to keep is in the designated folder on local machine.