Dell R710 (and possibly other) temperature-based fan speeds script

updatefans.sh

#!/bin/bash

# Script for checking the temperature reported by the ambient temperature sensor,
# and if deemed too high send the raw IPMI command to enable dynamic fan control.
#
# Also get CPU temps from lm-sensors and adjust fan speeds according to defined
# speed % which should be set according to your needs (each CPU model will vary)
#
# Requires:
# ipmitool – apt install ipmitool
# sensors - apt install lm-sensors
# bc - apt install bc

LASTSPEED=$(cat /tmp/lastspeed 2>/dev/null || echo 0)

function setfans () {
  speed=$1
  if [[ $speed == "auto" ]]; then
    # Enable automatic fan speed control
    ipmitool raw 0x30 0x30 0x01 0x01 >/dev/null 2>&1 &
    LASTSPEED=${speed}
    echo "[$(date)] $(hostname) FANS: AUTO (SYS: ${SYSTEMP}C, CPU: ${CPUTEMP}C)"
    echo "AUTO (SYS: ${SYSTEMP}C, CPU: ${CPUTEMP}C)" | systemd-cat -t updatefans
  else
    speedhex=$(echo "obase=16; $speed" | bc)
    # Enable manual fan speed control
    if [[ "$LASTSPEED" == "auto" ]] || [[ "$LASTSPEED" == "0" ]]; then
      ipmitool raw 0x30 0x30 0x01 0x00 >/dev/null 2>&1 # &
    fi
    ipmitool raw 0x30 0x30 0x02 0xff 0x${speedhex} >/dev/null 2>&1 &
    LASTSPEED=${speed}
    echo "[$(date)] $(hostname) FANS: ${speed}% (0x${speedhex}) (SYS: ${SYSTEMP}C, CPU: ${CPUTEMP}C)"
    echo "${speed}% (0x${speedhex}) (SYS: ${SYSTEMP}C, CPU: ${CPUTEMP}C)" | systemd-cat -t updatefans
  fi
}

# This variable sends a IPMI command to get the temperature, and outputs it as two digits.
SYSTEMP=$(ipmitool sdr type temperature | grep Ambient | grep degrees | grep -Po '\d{2}' | tail -1)

#highest of all core temps
CPUTEMP=$(sensors | grep high | cut -d "+" -f2 | cut -d "." -f1 | sort -n | tail -1)

# Use the cpu temperature to calculate an optimal fan speed compared to the temperature using the formula x^2/50
let "SPEED=$CPUTEMP**2/50"

# Ceil the value
SPEED=$(echo $SPEED | awk '{print int($1+0.5)}')

if [[ $SYSTEMP > 32 || $CPUTEMP > 65 ]]; then
  echo   "Warning: SysTemp or CpuTemp too high! Activating dynamic fan control! ($SYSTEMP C)"
  echo "Warning: SysTemp or CpuTemp too high! Activating dynamic fan control! ($SYSTEMP C)" | systemd-cat -p "warning" -t updatefans
  setfans auto
else
  setfans $SPEED
fi

echo $LASTSPEED > /tmp/lastspeed

Thank you, i like your optimal fan speed calc

FYI, I had to run sudo chmod -t /tmp in order to get $LASTSPEED to save