On my rasdpberry pi when i mount my usb disk (ext3 filesystem) just with mount /dev/sda1 /mnt/disk1 the disk gets io every 5 seconds jdbd2 shows up in iotop. So I remounted with -o noatime. Now the disk keeps quiet. Only backdraft is now files dont get a accesstime recorded. Now I read about relatime as option. Will check this tonight.