Spin down usb hard disk automatically if there is no activity | Depends: hdparm sdparm | Cron: */15 * * * * spindown.sh sda 10 (spin down sda if there is no activity for 10 minutes)

spindown.sh

#!/bin/sh

DISK=sda
TIMEOUT=600

if [ $# -ge 1 ] ; then
    DISK=$1
fi
if [ $# -ge 2 ] ; then
    TIMEOUT=$2
    TIMEOUT=$((TIMEOUT*60))
fi

status=`hdparm -C /dev/$DISK | grep -o standby`
if [ "$status" = "standby" ] ; then
    exit 0
fi

for i in `seq 1 $TIMEOUT` ; do
    io=`cat /proc/diskstats | grep "$DISK " | awk '{print $(NF-2)}'`
    if [ $io -gt 0 ] ; then
        exit 0
    fi
    sleep 1
done

logger "Sending standby command to /dev/$DISK"
sdparm -C stop /dev/$DISK > /dev/null

exit 0

For the record, you need to pass -r (readonly) for modern disks:

sdparm -C stop -r /dev/sdd

For the record, you need to pass -r (readonly) for modern disks:

sdparm -C stop -r /dev/sdd

Thanks. The -r parameter is not available for old sdparm versions, at least not available for my openwrt router.