iDrac 7 r720 ipmi fan control

fan-control.sh

#!/bin/bash
#
# Dell R720 dual-CPU fan control script
# Based on https://wiki.joeplaa.com/tutorials/how-to-control-dell-server-fanspeeds-with-ipmitool
# (which is itself based on https://github.com/brezlord/iDRAC7_fan_control)
#
# Monitors both CPU temps and controls fans based on the higher of the two.
# Falls back to iDRAC automatic control if temp exceeds threshold.
#
# Setup:
#   1. echo 'yourpassword' > ~/.ipmi_password && chmod 600 ~/.ipmi_password
#   2. chmod +x /usr/local/bin/fan-control.sh
#   3. Add to cron: */3 * * * * /usr/local/bin/fan-control.sh >> /var/log/fan-control.log 2>&1

IDRAC_IP="${IDRAC_IP:-169.254.0.1}"
IDRAC_USER="${IDRAC_USER:-"fan-op"}"
IDRAC_PASS_FILE="${IDRAC_PASS_FILE:-$HOME/.ipmi_password}"

# Temperature threshold above which iDRAC automatic control is re-enabled (°C)
TEMP_THRESHOLD=55

# Fan speed hex values (percent)
SPEED15="0x0f"
SPEED20="0x14"
SPEED25="0x19"
SPEED30="0x1e"
SPEED35="0x23"
SPEED40="0x28"
SPEED45="0x2d"
SPEED50="0x32"
SPEED55="0x37"

IPMI="ipmitool -I lanplus -H $IDRAC_IP -U $IDRAC_USER -f $IDRAC_PASS_FILE"

enable_auto() {
    echo "Restoring automatic fan control"
    $IPMI raw 0x30 0x30 0x01 0x01
}
trap enable_auto ERR TERM INT

echo "=== $(date '+%Y-%m-%d %H:%M:%S') ==="

# Read all temps in a single IPMI call, then parse each CPU from the result
TEMPS=$($IPMI sdr type temperature 2>/dev/null)
T1=$(echo "$TEMPS" | grep "0Eh" | cut -d"|" -f5 | cut -d" " -f2)
T2=$(echo "$TEMPS" | grep "0Fh" | cut -d"|" -f5 | cut -d" " -f2)

# Validate readings
if [[ -z "$T1" || -z "$T2" ]]; then
	echo "ERROR: Could not read CPU temps (T1='$T1' T2='$T2'). Falling back to automatic control."
	$IPMI raw 0x30 0x30 0x01 0x01
	exit 1
fi

echo "CPU1: ${T1}°C  CPU2: ${T2}°C"

# Use the higher of the two temps as the control variable
if [ "$T1" -ge "$T2" ]; then
	T=$T1
else
	T=$T2
fi
echo "Controlling on: ${T}°C"

# If temp exceeds threshold, hand control back to iDRAC
if [ "$T" -ge "$TEMP_THRESHOLD" ]; then
	echo "Above ${TEMP_THRESHOLD}°C threshold — enabling automatic fan control"
	$IPMI raw 0x30 0x30 0x01 0x01
	exit 0
fi

# Enable manual fan control
$IPMI raw 0x30 0x30 0x01 0x00

# Set fan speed based on temperature curve
if [ "$T" -le 25 ]; then
	echo "Setting fans to 15%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED15
elif [ "$T" -le 30 ]; then
	echo "Setting fans to 20%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED20
elif [ "$T" -le 35 ]; then
	echo "Setting fans to 25%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED25
elif [ "$T" -le 39 ]; then
	echo "Setting fans to 30%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED30
elif [ "$T" -le 42 ]; then
	echo "Setting fans to 35%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED35
elif [ "$T" -le 45 ]; then
	echo "Setting fans to 40%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED40
elif [ "$T" -le 47 ]; then
	echo "Setting fans to 45%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED45
elif [ "$T" -le 51 ]; then
	echo "Setting fans to 50%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED50
else
	# 43–44°C, just under threshold
	echo "Setting fans to 55%"
	$IPMI raw 0x30 0x30 0x02 0xff $SPEED55
fi