Ok so i have a client i am setting up his own cloud. I did the next cloud install with Mariadb, php7.4 and cert bot. He currently has a samba share set up going to his dell R720 with 10TB of storage.
I installed Nextcloud to the server and i mounted the drive array inside the files folder of a Nextcloud user to give access to all the clients to the server. Obviously this is not a good idea but i wanted to try it anyway… It seems to work ok, minus the sometimes extremely late folder updates on the client apps and incorrect reporting of disk space usage. Other than that the files actually sync… Now from what i see the client apps ask for a source and destination folder 1 folder is where the data is stored and the other is the remote location you are pulling from. But what about the server it self with all the data on it? if i used the sync application on the server i would have to have 2 of each file since the sync app asks for a source and destination folder. I would pick the same folders but I am sure that would cause a loop. My question is… well this doesn’t make sense to me. It seems like there is a big feature missing to the software. That being is if you already have a server with a lot of data on it. We need a pre sync feature to sync data already on the server without having to install a sync app on the server to get the files synced with the database. Not only that you have to have 2 of each file if you want to sync files that are already on the server. Not sure if i am making any sense to you guys. Is there a cronjob i can do to get the database up to par with the folders them selfs? Otherwise i will have to install that sync app on the server. Than choose 1 folder as a source on the server and 1 as a destination. This also requires 2x the storage space just to get the files in sync that are already on the server…
Hmm… 
Maybe this helps?:
Hi @finalturismo, there is a command to update the nextcloud database when you move data manually ( add or move data without using nextcloud ) :
sudo -u www-data php /var/www/nextcloud/occ files:scan ( make sure to set the right path of your nextcloud server folder)
the server will rescan all folders of users and add the new files you have added.
please check documentation for admin: https://docs.nextcloud.com/server/stable/admin_manual/configuration_server/occ_command.html