Check log of actions the machine has performed? (NUC nextcloud server on Debian 10)

I'm running nextcloud (only I access it), and emby media server (again, only I access this). Yet sometimes when I'm not using it, I here the hard drive clicking as though it's reading or writing. Idk what it would be. Maybe backups but I have that set to once a week, and I hear noises nearly everyday even though I'm not using it.

Is there any log I can check to see what actions have been happening on the machine? So I can figure out what is reading and rewriting to the drive?