Ubiquiti UNAS and UNVR Fan Control Service

This is a fan control service using a linear fan curve that is deployed over SSH and runs via systemd. It's specifically designed for the Ubiquiti UNAS products to keep the HDDs cooler than the default fan controller.

It polls CPU and HDD temps to compute a fan speed once every minute, aiming to run the fan at the quietest speed that also keeps the HDDs under 40ºC (configurable). It overrides the Ubiquiti quiet/balanced/fast fan presets and persists between reboots and updates.

Supported devices:

• UNAS Pro
• UNAS Pro 8 (confirmed by @toscano)
• UNAS 2 (confirmed by @Jordo-o)
• UNVR (confirmed by @gormic75)

Unconfirmed devices:

• UNAS Pro 4
• UNAS 4
• UNVR Pro
• ENVR (likely has extra sensors)

Help confirm device support!

Please follow this checklist when confirming device support:

• Run the /root/fan_control.sh script manually on your UNAS (or query.sh remotely), which will output logs with sensor readings.
• Confirm CPU and all HDD temperature sensors are reading correctly, and there is a temperature reading for each of your installed HDDs. Example output below.

  /sys/class/hwmon/hwmon0/temp1_input CPU Temperature: 44ºC
  /sys/class/hwmon/hwmon0/temp2_input CPU Temperature: 35ºC
  /sys/class/hwmon/hwmon0/temp3_input CPU Temperature: 55ºC
  /sys/class/thermal/thermal_zone0/temp CPU Temperature: 55ºC
  /dev/sda HDD Temperature: 34°C
  /dev/sdb HDD Temperature: 34°C
  /dev/sdc HDD Temperature: 35°C
  /dev/sdd HDD Temperature: 34°C
  /dev/sde HDD Temperature: 36°C
  /dev/sdf HDD Temperature: 34°C
  /dev/sdg HDD Temperature: 35°C
  Max HDD Temperature: 36°C
  CPU Temperature: 55°C
  

• Confirm the fan speed is being set correctly. Note that Unifi OS can also change the fan speed, so occasional mismatches between the set and read fan speeds are acceptable, and fan_control.sh can be run multiple times. Example output below.

  Min Fan Speed: 39
  HDD Fan Speed: 56
  CPU Fan Speed: 63
  Final Fan Speed (Max): 63
  Fan /sys/class/hwmon/hwmon0/pwm1 has been set to 63/255, and is reading as 63/255.
  Fan /sys/class/hwmon/hwmon0/pwm2 has been set to 63/255, and is reading as 63/255.
  Fan /sys/class/hwmon/hwmon0/pwm3 has been set to 63/255, and is reading as 63/255.
  

• When running the systemd service, confirm the HDD temperatures and fan speeds reach your expected range after 30+ minutes of operation.

Please raise a GitHub issue to confirm if this script is working (or not!), or to log what the issue is and we can try to add support if you're willing to help us test. Patches for new temperature sensors or fan devices are also welcome. Thanks!

Deployment

Remote SSH Deployment

• Deploy remotely: ./deploy.sh $HOST to deploy to the UNAS over SSH.
• Query remotely: ./query.sh $HOST to query temperatures and fan speeds.

Manual Deployment

To be run on the UNAS Pro directly as root.

# Download latest fan_control.sh and fan_control.service from GitHub to their destinations
wget -O /root/fan_control.sh https://raw.githubusercontent.com/hoxxep/UNAS-Pro-fan-control/refs/heads/main/fan_control.sh
wget -O /etc/systemd/system/fan_control.service https://raw.githubusercontent.com/hoxxep/UNAS-Pro-fan-control/refs/heads/main/fan_control.service

# Make fan_control executable
chmod +x /root/fan_control.sh

# Set up and restart the fan_control service
systemctl daemon-reload
systemctl enable fan_control.service
systemctl restart fan_control.service

# Check fan_control.service is running
systemctl status fan_control.service

Query temps and fan speed (Manual)

Simply run the fan_control.sh script to query current temperatures and computed fan speed.

/root/fan_control.sh

Temporarily Disable (Manual)

# stop service, will still start fan_control again on next reboot
systemctl stop fan_control.service

# stop and disable service, won't start fan_control on next reboot
systemctl disable fan_control.service

And you can re-enable with:

systemctl enable fan_control.service
systemctl start fan_control.service

Uninstall (Manual)

systemctl disable fan_control.service
rm /root/fan_control.sh
rm /etc/systemd/system/fan_control.service
systemctl daemon-reload

Algorithm Parameters

Adjust the fan_control.sh parameters to suit your needs. These fan curves, specifically MAX and TGT temps, are currently set to keep the drives under 40ºC in a warm cabinet (30ºC ambient).

• CPU_TGT=50: The target CPU temp in celcius, at which fans will run at MIN_FAN.
• CPU_MAX=70: The max CPU temp in celcius, where fans will run at 100%.
• HDD_TGT=32: The target HDD temp in celcius, at which fans will run at MIN_FAN.
• HDD_MAX=50: The max HDD temp in celcius, where fans will run at 100%.
• MIN_FAN=39: The minimum fan speed, 15% of 255 (fan speeds are out of 255).

Fan speed is set linearly between the TGT temp (MIN_FAN fan speed) and MAX temp (100% fan speed). The max temp of all HDDs is used as the HDD temp, and the max computed fan speed between the CPU and HDD speeds is used as the fan speed. Pseudocode and fan speed chart below.

CPU_TEMP = max(all CPU temps)
HDD_TEMP = max(all HDD temps)

# compute point linearly between min and max
CPU_FAN = (CPU_TEMP - CPU_MIN) / (CPU_MAX - CPU_MIN)
HDD_FAN = (HDD_TEMP - HDD_MIN) / (HDD_MAX - HDD_MIN)

# clip to range [MIN_FAN, 100%]
FAN_FRAC = max(MIN_FAN, CPU_FAN, HDD_FAN)
FAN_SPEED = 100% * min(FAN_FRAC, 1)

Tips for setting parameters

Typically we leave the MAX variables fixed, and experiment with the TGT to find an ideal fan speed/noise/temperature trade off.

Set the HDD and CPU max temperatures where you would like to run the fans at 100%, where the system is definitely too hot. Then experiment with different HDD and CPU target (TGT) temperatures to where you would like to run the CPU at the minimum fan speed. A lower TGT temperature will result in higher fan speeds which should keep the system cooler.

Look out for which temperature is setting the fan speed. The HDD and CPU temps compute two separate fan curves, and the higher computed fan speed is chosen. The systemd service will check temperatures and set fan speeds once every minute.

Remote edit and redeploy

Adjust algorithm parameters in fan_control.sh remotely and redeploy remotely with ./deploy.sh $HOST. Temperatures and computed fan speeds can be queried with ./query.sh $HOST.

Manual edit and redeploy

Adjust algorithm parameters in /root/fan_control.sh, and then restart the systemd unit with:

systemctl daemon-reload
systemctl restart fan_control.service

Temperatures and fan speeds can be queried by running /root/fan_control.sh directly.

Requirements

• Unifi OS: UNAS Pro 4.2.6 and beyond.
• Deployment: Root SSH access to the UNAS Pro via an SSH key and ~/.ssh/config host configured.