Maybe this is a solution for you (untested): In DSM 4.x you have a Jobplanner where you can create a plan for a user script. The Code for the Script: #!/bin/sh ping -c 1 YOUR-PC-NAME >/dev/null if [ $? == 1 ]; then echo "offline" sh /var/packages/btsync/scripts/start-stop-status stop else echo "online" sh /var/packages/btsync/scripts/start-stop-status start fi Replace the Computername. Start daily at 0:00; repeat every hour; end at 23:00. Run script as user root. Please tell us if with this solution your HDDs can sleep.