Is there a way to stop my server to scan the HDD every single day at startup?

there sure is, in the admin dashboard, goto Scheduled Tasks and find Scan Media Library, click it and then delete the trigger

Under "Scheduled Tasks" in the admin panel you can remove the on application start trigger for the library scan.

@zShxck

You can control the tasks that run, and their frequency, under "Dashboard -> Scheduled Tasks"

THANK YOU ALL!