Running both 6.9.2 and 6.10.0-rc1 and having the same issue, disabled all Docker containers, disabled Auto Fan and still having this issue. My disks are SAS if it's relevant.
They do spin down at the 15 min mark (as I have them configured) and then, few moments later, spin up again. I was playing with suggestion on this thread and noticed that after removing Auto Fan, seemed like it worked, my disks stayed spin down for a good minute or two and then they started again, in the logs, I could see:
Aug 29 05:48:49 Tower emhttpd: spinning down /dev/sde
Aug 29 05:48:49 Tower SAS Assist v0.86: Spinning down device /dev/sde
Aug 29 05:50:30 Tower kernel: sd 1:0:3:0: [sde] tag#786 CDB: opcode=0x85 85 06 20 00 00 00 00 00 00 00 00 00 00 40 e5 00
Aug 29 05:50:32 Tower emhttpd: read SMART /dev/sde
the time for the `emhttpd: read SMART /dev/sde` corresponds exactly to the time my disks spun up again, so it is possible that the UI is actually causing this issue?