Weird tidbit in the home server: disk /dev/hdc, a WDC WD3200AAJB will not go to standby mode on the timer. With hdparm -S 59 /dev/hdc no standby mode happens, while I am sure nothing accesses the drive (unmounting all partitions and stopping smartmontools). When I force it to standby with hdparm -y /dev/hdc it will stay in standby mode until the partition is accessed again.