Как заставить жесткий диск остановить вращение?

function remove_dev {
    say "Removing the backup device..."
    DEVFILE="/sys/class/scsi_host/host$DEV_HOST/device/\
             target$DEV_HOST:$DEV_BUS:$DEV_TARGET/\
             $DEV_HOST:$DEV_BUS:$DEV_TARGET:$DEV_LUN_ID"
    if grep -q `ls "${DEVFILE// }/block"` /proc/mounts
    then
        die "ERROR: The backup disk is still mounted."
    fi;
    echo "1" > "${DEVFILE// }/delete"
}

if [ "$1" = "spindown" ]; then
    if /sbin/vgchange -an $VGr; then
        [ -n "$DEV" ] && /usr/bin/sg_start --stop /dev/$DEV
        [ -n "$DEV" ] && echo 1 > /sys/block/$DEV/device/delete
    else
        echo "Can not deactivate $VGr"
    fi
fi

if [ "$1" = "spinup" ]; then
    for scan in /sys/class/scsi_host/host*/scan; do
         echo 0 1 0 > $scan
    done
    echo "sleep 20"
    sleep 20
    vgchange -ay $VGr
fi