#!/bin/bash

# This is to control the speed of the system fan on a QNAP TS-410 running
# Debian depending on the temperatures the harddisks report via SMART.
# AFAIK it should work on every QNAP TS-41x as long as it runs
# Debian (tested on 6.0.2, "squeeze").
#
# (c) 2011 Robert Waldner
# License: GPLv2, see http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
#
# Needs smartmontools installed, obviously, and qcontrol running.
# It's ugly, I know.
# Hopefully there'll be something built-in to qcontrol at some point.

set -e
   
DISKS="a b c d"
MAXTEMP=34
MEDTEMP=30
MINTEMP=20
# writing to /var/log would wake the disks when idle
LOG=/tmp/fancontrol.log
DATE=`date --rfc-822`
# don't make the loop too tight, at least my disks block for 1-2 seconds
# while answering SMART requests
SLEEP=60
LASTSTATE="undef"
TEMPFILE=/tmp/disktemps
   
while true; do
   DATE=`date --rfc-822`
   LOGLINE=`echo -n "$DATE:"`
   HIGHEST=0
   
   for DISK in $DISKS ; do
      # hddtemp would wake the disks, smartctl allegedly doesn't
      TEMP=`/usr/sbin/smartctl -a "/dev/sd$DISK" \
               | grep Temperature_Celsius \
               | sed -e s/".*\-"//g -e s/"(.*"//g -e s/"\ "//g`
      LOGLINE=`echo -n "$LOGLINE sd$DISK: $TEMP;"`
      TEMPLINE=`echo -n "$TEMPLINE $TEMP"`
      if [ "$TEMP" -gt "$HIGHEST" ]; then
         HIGHEST="$TEMP"
      fi
   done

   # write the current temps to a file for easy access from other stuff.
   # file must not grow, and should not reside on any physical disk
   # so as not to wake sleeping drives.
   echo "$TEMPLINE" >"$TEMPFILE.1"
   mv "$TEMPFILE.1" "$TEMPFILE"
   
   # damn qcontrol exits with something <> 0 even on success
   if [ "$HIGHEST" -ge "$MAXTEMP" ]; then
        if  [ "$LASTSTATE" != "full" ]; then
           LOGLINE=`echo -n "$LOGLINE Fan: full"`
           LASTSTATE="full"
           qcontrol fanspeed full || true
           echo "$LOGLINE" >>"$LOG"
        fi
     elif [ "$HIGHEST" -ge "$MEDTEMP" ]; then
        if [ "$LASTSTATE" != "medium" ]; then
           LOGLINE=`echo -n "$LOGLINE Fan: medium"`
           LASTSTATE="medium"
           qcontrol fanspeed medium ||  true
           echo "$LOGLINE" >>"$LOG"
        fi
     elif [ "$HIGHEST" -ge "$MINTEMP" ]; then
        if [ "$LASTSTATE" != "silence" ]; then
           LOGLINE=`echo -n "$LOGLINE Fan: silence"`
           LASTSTATE="silence"
           qcontrol fanspeed silence || true
           echo "$LOGLINE" >>"$LOG"
        fi
     else
        echo "$DATE: CONFUSION; last state: $LASTSTATE; highest temp: $HIGHEST; trying to set the fan to full and exiting" >>"$LOG"
        qcontrol fanspeed full || true
        exit
   fi
   
   sleep "$SLEEP"
   
done