Written for / tested on: Synology DS218+

Step 1: Make use of hibernation

Your NAS is quiet, if it spins down your HDDs:

  • Activate hibernation (+ advanced hibernation) after a short time period (10 min): Control Panel > Hardware & Power > HDD Hibernation.
  • Make sure you disable Quickconnect as it prevents hibernation

Step 2: Custom FAN-profile

We will create a custom fan profile to make the fans spin slower and also stop (turn off) if not needed.


  1. Goto Control Panel > Hardware & Power > HDD Hibernation and enable the SSH Service
  2. Open your terminal (or putty on Windows) and ssh into your NAS: ssh <yourUsername>@<yourNasIP>
  3. Be a bad boy and switch to the root account: sudo -i

Turning off FAN health check

In order to prevent error messages like 'FAN stopped working' (that are going to clutter your web-interface) as soon as we turn off the fan on purpose, we need to disable the fan health check:

  1. Create a startup script: vim /usr/local/etc/rc.d/fan_check_disable.sh
  2. Insert (press i):
    echo 0 > /sys/module/apollolake_synobios/parameters/check_fan
  3. Save and exit (ESC > type :wq > ENTER)
  4. Set correct permissions: chmod 755 /usr/local/etc/rc.d/fan_check_disable.sh
  5. Done!

HINT: if /sys/module/apollolake_synobios/parameters/check_fan does not exist, search your filesystem for a file called check_fan (please google if you don't know how to search a file via console)

Creating the profile

Now were going to define our own very quiet fan profile that will keep our NAS as quiet as possible without breaking something by letting it overheat.

  1. Backup /usr/syno/etc.defaults/scemd.xml
  2. Open your fan profiles: vim /usr/syno/etc.defaults/scemd.xml
  3. Find <fan_config hibernation_speed="UNKNOWN" type="DUAL_MODE_LOW" threshold="6" period="20">
  4. Replace content between <fan_config ..> and </fan_config> with (inside vim, press i to enter insert mode, press ESC to go back to command mode and type :wq to write changes and quit vim):
<disk_temperature action="NONE" fan_speed="01%40hz">0</disk_temperature>
<disk_temperature action="NONE" fan_speed="10%40hz">41</disk_temperature>
<disk_temperature action="NONE" fan_speed="20%40hz">46</disk_temperature>
<disk_temperature action="NONE" fan_speed="35%40hz">48</disk_temperature>
<disk_temperature action="NONE" fan_speed="50%40hz">50</disk_temperature>
<disk_temperature action="NONE" fan_speed="70%40hz">54</disk_temperature>
<disk_temperature action="NONE" fan_speed="99%40hz">58</disk_temperature>
<disk_temperature action="SHUTDOWN" fan_speed="99%40hz">61</disk_temperature>

<cpu_temperature action="NONE" fan_speed="01%40hz">0</cpu_temperature>
<cpu_temperature action="NONE" fan_speed="10%40hz">57</cpu_temperature>
<cpu_temperature action="NONE" fan_speed="20%40hz">62</cpu_temperature>
<cpu_temperature action="NONE" fan_speed="50%40hz">65</cpu_temperature>
<cpu_temperature action="NONE" fan_speed="99%40hz">80</cpu_temperature>
<cpu_temperature action="SHUTDOWN" fan_speed="99%40hz">90</cpu_temperature>
  1. Clone /usr/syno/etc.defaults/scemd.xml to /usr/syno/etc/scemd.xml with the following command: cp /usr/syno/etc.defaults/scemd.xml /usr/syno/etc/scemd.xml
  2. Restart your NAS and youre done!

Step 3: Install a new FAN

Buy and install a new FAN, for example the Noctua NF-A9 FLX*.