• A simple fan control script that turns off the fan at idle/low temperatures, which otherwise will run constantly by default.

• Cut out the protective piece of plastic from the back plate, enlarged the opening, added some padding. After that the unit is MUCH quieter
  ondro727's Fan Hack

• Fan does run all the time
• DNS-323
• Disk 1 spins up every 10 minutes
• DNS-323 Disassembly Pictures

Query and set the FAN Speed control
Usage: fanspeed [function]

Functions:
h show this help
w rpm, set fan speed(rpm range:1935~30000)
g get fan speed

fanspeed g

Returns the fan's current speed in rpm (revolutions per minute).

fanspeed w 2500

Sets the fan's speed to 2,500 rpm.

fanspeed w 0

Sets the fan's speed to 0 rpm (Stops the fan). The fancontrol process appears to restart the fan within a minute if it's running.

fanspeed w 30000

Not recommended! What happens!? Does anyone have the courage to report? : )

• What are the best ways to detect if the hard drive is in sleep mode (for use in a script)?
• Does anyone have the source?

\sys\crfs\sbin\fanspeed

Query and set the temperature sensor
Usage: temperature [function]

Functions:
h - show this help
w [1,2] degree - set temperature degree in register 1:Thyst 2:Tos
g [0~2] - get temperature in register 0:temperature 1:Thyst 2:Tos

temperature g 0

Returns the current temperature. Anybody know where the temperature probe is located?

temperature g 1

Returns the hysteresis Thyst register value/limit. Default setting = 75 degrees C / 167 degrees F.

temperature g 2

Returns the Overtemp shutdown Tos register value/threshold. Default setting = 80 degrees C / 176 degrees F.

• Does anyone have the source? (reverse engineered code: http://www.inreto.de/dns323/utils/)
• Is documentation essentially right?: Thyst & Tos Information - found by @galf
• Does anyone know whether 'temperature g 0' ever reports in Celsius? The wiki's first script seems to think so, but reports so far seem to point to the usage of Fahrenheit as standard.

\sys\crfs\sbin\temperature

Appears to be a daemon, running all the time by default.

• It appears to query the temperature and set appropriate fan speeds approximately every 60 seconds.
• Does anyone know what it does, exactly?
• Does anyone have the source? (reverse engineered code: http://www.inreto.de/dns323/utils/)

\sys\crfs\sbin\fancontrol

I think this can be useful to you as it would to me as a newbie who is technically challenged. This is a feature that should have been implemented from the factory, as it makes no sense to have the fan running all the time. It's quite simple to do, and it effectively reduces noise and wear. Please feel free to make corrections.

The Quick and Easy

1. Download fonz_funplug-0.3_plus_fan_control.rar.
2. Open the .rar archive (use WinRAR), drop the four files in the archive into your root folder (e.g. /Volume_1/) via ftp or just by simple drag and drop. Reboot immediately.
3. After the power light stops blinking, wait one minute. Then telnet into your unit's local IP (default is 192.168.0.32) using a telnet/ssh client (try PuTTY) and type temperature g 0 to check your DNS-323's temperature readings.
4. If the temperature shows Fahrenheit unit, you are done. If it's below 108F, the fan should have stopped. You can type fanspeed g 0 to check the fan RPM.
5. If the temperature shows in Celsius, in the same telnet screen, type:

   mv /mnt/HD_a2/ctrl_fanspeed.C /mnt/HD_a2/ctrl_fanspeed.sh
   reboot

   The last command of course reboots your unit. After which you can recheck the temperature and fan. If it's below 43C, the fan should have stopped, and you are done.

The Nitty Gritty Steps

1. Get a text editor like Notepad++ to save text files in linux format (LF).
2. Create a new text file called fun_plug (no extensions), with the following line:

   /mnt/HD_a2/ctrl_fanspeed.sh

   save the text file with linux format (LF) to the root directory of your DNS-323 drive (e.g. /Volume_1/ or just drag and drop into your mapped drive).
   Alternatively, you can get fonz's fun_plug pack (which adds telnet feature among other things) and add the above line at the end of the included fun_plug file (don't drop it into /mnt/HD_a2/fun_plug.d/start/ directory as it's a loop that stops any script that follows it from loading).

3. Create another text file, copy and paste the “general use” version of the fan-control script below. Adjust the parameters to your liking (description in comments), though it works fine without any modification (assuming your unit reports temperature in Fahrenheit). Save the file as ctrl_fanspeed.sh at the root directory (e.g. /Volume_1/) of your DNS-323 drive, same location as the fun_plug file.
4. Reboot the DNS-323 using D-Link's control page and you are done!

You should notice that immediately after booting (when the power light stops flashing) the fan stops. That is if your drive is cooler than the lower limit set in the script (default 108F or 42C), which will eventually be the case after HD spins down at idle, or if you boot the unit cold.

Also make sure your DNS-323 unit reports temperature readings that matches the temperature unit in the script, which is in Fahrenheit (Important! You don't want 108C as lower limit!). You can do this with a simple telnet command temperature g 0. You will need to convert the temperature parameters in the script if your DNS-323 returns temperature readings in Celsius.

Is it safe to assume all US models are reporting in Fahrenheit? Mine does.

This sample script changes the speed of the fan based on the reported temperature. Note that this script is written with temperature reference in Celsius. By running temperature g 0 via telnet you can see what temperature-unit your box uses. The parameter-values are only given as examples.

The script can be run in the background where it will remain active and periodically update the speed of the fan. To avoid clashes with the fancontrol process, it is probably best to kill it before this script is run.

#!/bin/sh
#
# ctrl_fanspeed.sh  Script for controlling the speed of the fan on an DNS-323
#
#At temperatures below T1 it sets the fan to RPM1, while at temperatures above T2 it sets it to RPM2. 
#At temperatures between T1 and T2 it linearly interpolates the speed of the fan from RPM1 at T1, to RPM2 at T2. 
#The temperature is checked every INTERVAL seconds.
 
INTERVAL=15
T1=40
T2=60
RPM1=1000
RPM2=6000
 
while [ 1 ]
do
  T=`temperature g 0|sed -n ' s/<temperaturertc>: get temperature =//p'`
  NEW_RPM=`expr  \( $T \> $T2 \) \* $RPM2 \| \( $T \< $T1 \) \* $RPM1  \| $RPM1 + \( $RPM2 - $RPM1 \) \* \( $T - $T1 \) \/ \( $T2 - $T1 \)` 
  fanspeed w $NEW_RPM 
  sleep $INTERVAL
done

This script automatically kills the factory fancontrol process and loads the script into RAM disk, so to avoid periodic disk spin-ups as the script runs continuously. You can also comment-out (adding # in front of) the 3 lines following # Create a logfile on the RAM-disk as well as every line that starts with echo to turn off logging. This script is written with temperature reported in Fahrenheit. You will have to convert the T1/T2 parameter values if your unit reports in Celsius.

It's a more polished example of a script to control fan speeds. Please read through the thread Fan does run all the time before you install this script.

#!/bin/sh
#
# This script was created at http://wiki.dns323.info by FIB,
# it has been slightly modified by leper (with help from
# fonz). It sets the fanspeed of the device depending on 
# the temperature, which is measured in Fahrenheit. If 
# your box measures temperature in Celsius, you need to 
# edit it to work.
# Additional changes by gartylad.
 
# Set the path to use RAM-disk instead of harddrive, to 
# execute from. This is done so that the disks will go
# into sleep mode, while the script is running.
PATH=/usr/bin:/bin:/usr/sbin:/sbin
 
# Create a logfile on the RAM-disk.
LOGDIR=/log
FANLOGFILE=${LOGDIR}/fan_ctrl.log
mkdir -p ${LOGDIR}
 
# Kill the old fan controller.
kill -9 `pidof fancontrol`
echo "Fancontrol killed. Installing fan_ctrl.sh" >${FANLOGFILE}
 
# With temps between T1 and T2, the script automatically
# lowers/raises the fan speed between RPM1 and RPM2. This
# it does every update_interval seconds.
update_interval=60
T1=108
T2=140
RPM1=2300
RPM2=4500
 
while [ 1 ]
do
  T=`temperature g 0`
  T=${T##*=}
  # Check if temperature has fallen below T1 value
  if [ $T -lt $T1 ]; then
	# Temp below T1 fan stops
	CALCTEMP=`expr 0` 
  else
	# Temp above T1 fan starts
	CALCTEMP=`expr \( \( $T2 \< $T \) \* $RPM2 \) \| \( \( $RPM1 + \( $RPM2 - $RPM1 \) \* \( $T - $T1 \) \/ \( $T2 - $T1 \) \) \& \( $T \>= $T1 \) \)`
  fi
  CONVFTOC=`expr \( \( $T - 32 \) \* 10 + 9 \) \/ 18`
  newRPM=${CALCTEMP}
  fanspeed w $newRPM  
  echo `date`" ::CURRENT::" $T"F" ${CONVFTOC}"C -- fanspeed:" $newRPM "(written to "${FANLOGFILE}")." >>${FANLOGFILE}
  # wait for next cycle
  sleep $update_interval
done

• ADDA 40mm Fan Performance Curves
• Options (??not sure??)