Constand disk write by MariaDB while using Nextcloud

MariaDB is constantly writing data to my ssds. Nextcloud seems to cause most of the writes, because when I use NC the write goes up even though I am only browsing my files.

How could I measure where the disk writes originate from? What is a normal/expected disk write when there is no user activity? Is there some kind of log written to db explaining constant writes?

Hope someone can help me getting more insight to mariadb.

Nextcloud version (eg, 12.0.2): 18.0.1
Operating system and version (eg, Ubuntu 17.04): Debian 9
Apache or nginx version (eg, Apache 2.4.25): Apache
PHP version (eg, 7.1): 7.14

Use the integrated log functionality of mariaDB:

I have checked the general query log. But it does not seems to be filled with oversurprisingly amount of update or insert statements.

With watch ls -la I tried to check for updates on data files. How could I track what file is producing the write operation?

Thanks a lot, also from my SSDs

If you want to monitor file access fatrace is probably the tool you are looking for.
https://packages.debian.org/stretch/fatrace