With the new DSM 6.1.1-15101 it’s FINALLY possible to schedule raid scrubbing, without modifying through shell commands. Open Control panel -> Task Scheduler:   Choose Create -> Scheduled Task -> Raid Scrubbing: Enter task name: Choose the “Schedule” tab:   Leave it as you like, but monthly is preferred! Press OK! And your “Raid Scrubbing” task is enabled and ready to run: 🙂