Mount / Link some some folder to nextcloud


I’ve been using Docker to host my Nextcloud application for a long time. On the same server, I’m running a scan server, which contains a lot of PDF files in one directory. I have a backup mechanism that backs up all data once a week. However, I’ve been wondering if there is a better backup solution. Since I have two clients connected to Nextcloud, which run on a daily basis (and they have enough disk space), it could be a great idea to use them as a backup medium. So, I thought, what if I connect the PDF folder with the Nextcloud app, to force all clients that start their system to backup the current state of the PDF? One benefit would be faster access without the web UI of my scan server.

However, I think I might run into some limitations, like file permissions, and I’m not sure if Nextcloud is building some synchronization index tables, which could make it problematic just to add a new folder to sync into their app structure.

So my question is, how can I add (mount) a foreign folder from my host system into my Nextcloud Docker container and let it synchronize to all of my client systems (only one specific user should sync, not all users)?

Thank you.

A sync is not a backup. Discard the idea that the Nextcloud client is somehow a backup solution for you.

Explain it. Maybe you can improve it. With incremental backups you only need e.g. 10% of the backup space.

Excuse me, but I just ask for the technical possibility to mount a different folder into my nextcloud instance without changing internal SQL-tables and stuff like that. I wrote that it would be a nice benefit to have scanned pdf in my cloud solution. So its not just a backup thing, it would make my live a little bit easier.
I did not want to discuss if nextcloud could be a replacement of a backup mechanism or not…