A script to adjust the fan speed on a Supermicro X9 motherboard based on hard drive temperatures.

coolhddx9.py

#!/usr/bin/env python3
"""A script to adjust the fan speed on a Supermicro X9 motherboard based on 
hard drive temperatures.

Install to `/usr/local/sbin/coolhddx9` for use with the associated systemd
service and timer.

"""

import glob
import os
import subprocess


MAX_TEMP = 39  # Magic number from a differnt script found online

FULL = '0x01'  # "Maximum cooling"
OPTIMAL = '0x02'  # "Balanced fan speed and power consumption"


def get_temp(hdd):
    """Get the temperature of `hdd` from `smartctl`.
    
    Arguments:
        hdd (str): The path to a hard drive block device.

    Returns:
        int: The temperature of `hdd` or 0 if a temperature can't be found.
    
    """
    try:
        lines = subprocess.check_output(['smartctl', '--attributes', hdd])
    except subprocess.CalledProcessError as err:
        print('Error:', err)
        return 0
    for line in lines.split(b'\n'):
        if b'Temp' in line:
            # Sometimes there is a "(Min/Max n/n)" at the end of the line.
            #  This gives "n/n)" in the last index.
            try:
                # No min/max
                return int(line.split()[-1])
            except ValueError:
                # Min/max. Use a different index.
                return int(line.split()[-3])
    print('Error: No temp found for', hdd)
    return 0


def set_mode(mode):
    """Set the fan mode of the motherboard."""
    proc = subprocess.run(['ipmitool', 'raw', '0x30', '0x45', '0x01', mode],
                        stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    if proc.returncode != 0:
        print('Error:', proc.stdout)


def _main():
    for hdd in glob.glob('/dev/sd[a-z]'):
        if get_temp(hdd) > MAX_TEMP:
            set_mode(FULL)
            return
    set_mode(OPTIMAL)


if __name__ == '__main__':
    _main()

coolhddx9.service

[Unit]
Description=HDD tempurature manager

[Service]
Type=oneshot
ExecStart=/usr/local/sbin/coolhddx9

coolhddx9.timer

[Unit]
Description=HDD tempurature manager

[Timer]
OnBootSec=10m
OnUnitActivate=10m
Unit=coolhddx9.service

[Install]
WantedBy=timers.target