Ubiquiti UNAS Pro 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 Pro to keep the HDDs cooler than the default fan controller.

It polls CPU and HDD temps (via SMART) to compute a fan speed once every minute. It persists between reboots and most updates, and can be quickly re-deployed if not.

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.

# 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
systemctl status fan_control.service

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, at which fans will run at MIN_FAN.
• CPU_MAX=70: The max CPU temp, where fans will run at 100%.
• HDD_TGT=32: The target HDD temp, at which fans will run at MIN_FAN.
• HDD_MAX=50: The max HDD temp, 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)

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.