Linux and unwanted disk spinups

Some process was spinning my suspended USB disks back up every few minutes which is bad, mmkay. To monitor processes accessing disks I used following commands

Enable logging:
service rsyslog stop
echo "1" >/proc/sys/vm/block_dump
while true; do dmesg -c; sleep 1; done

Disable logging:
echo "0" >/proc/sys/vm/block_dump
service rsyslog start