Take manual control of the fans on a Dell PowerEdge over IPMI and run them on your own temperature curve, so a server that lives in a home or an office is near-silent at idle instead of sitting at the BMC's noisy default.
Answer this first. It decides whether the rest of the page is worth your time.
| Generation | Models | Works |
|---|---|---|
| 11G | R310, R410, R510, R610, R710, T310, T410 | Yes |
| 12G | R320, R420, R520, R620, R720, T320, T420 | Yes |
| 13G | R430, R530, R630, R730, T430, T630 | Yes |
| 14G and newer | R440, R640, R740, R650, R750 | No |
14G and newer iDRAC firmware blocks the raw fan commands this depends on. There is no workaround in this repo. If you are on 14G+, your options are iDRAC's own thermal profiles under Configuration > System Settings > Hardware Settings > Fans, which is coarse, but it is what you have.
Check in ten seconds on hardware you already own:
ipmitool raw 0x30 0x30 0x01 0x00 && echo "manual mode accepted"
ipmitool raw 0x30 0x30 0x01 0x01 # and straight back to automaticIf the first command errors, your firmware has blocked it and nothing here will help.
A PowerEdge runs loud for three different reasons. This project fixes one of them. Working out which one you have first will save you an afternoon.
1. The BMC is simply conservative. It idles around 30% for no thermal reason, and it has done that since the day you got it. This is the case this project is for: take manual control, run a lower curve.
2. A non-Dell PCIe card is forcing a ramp. Fit a third-party HBA, NIC, or GPU and the firmware cannot read its thermals, so it applies a blanket cooling response and holds the fans at a floor regardless of temperature. The tell is fans pinned at a fixed speed while every sensor reads cool, starting the day you added the card.
This script does not fix that one. There is a separate, widely circulated raw iDRAC command that disables the third-party PCIe cooling response on some 13G firmware. I have not tested it and it is deliberately not wired into this script, so treat it as a lead rather than a recipe: search for "disable third-party PCIe card default cooling response". If a manual curve does not drop your noise, this is the most likely reason.
3. Something is genuinely wrong. A failing fan whining at full tilt, a heat
sink packed with dust, a hot room. Overriding the curve on a box that is hot
for a real reason is how hardware dies. Look at ipmitool sdr type fan and
your inlet temperature before reaching for software.
A small Bash daemon: read one temperature sensor every 30 seconds, set a fan percentage from a tiered curve you define. Runs on the server itself, or across the network against a remote iDRAC.
The parts that are easy to get wrong, and are handled:
- Hysteresis. Stepping down requires the temperature to fall a couple of degrees below the tier boundary, so the fans do not hunt when you idle right on a threshold.
- Failsafe. Dell's automatic control is restored on exit, on
SIGTERM/SIGINT, and if a sensor read fails. A dead sensor hands the fans back to the BMC and leaves them there until it reads again, rather than flapping between modes once per interval. - Preflight. A missing
ipmitool, an unreadable sensor name, or a malformed curve fails before the BMC is taken out of automatic mode, so a typo cannot leave your fans owned by a script that already died.
Requires ipmitool and Bash 4+. Nothing else.
Manual fan control means you are responsible for keeping the hardware cool. A bad curve can cook a server. The failsafes above shrink the blast radius; they do not transfer the responsibility. Test under sustained load before you trust it, and keep the top tier aggressive.
sudo install -m 0755 fan-control.sh /usr/local/bin/fan-control.sh
sudo cp fan-control.conf.example /etc/dell-ipmi-fan-control.conf
sudo chmod 600 /etc/dell-ipmi-fan-control.conf # if it holds an iDRAC passwordFind your temperature sensor:
fan-control.sh list-sensorsPick one (commonly Temp) and set SENSOR_NAME in the config file. Dual-socket
boxes expose two sensors under that same name; the hottest reading is the one
the curve is applied to.
sudo cp dell-ipmi-fan-control.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now dell-ipmi-fan-control
journalctl -u dell-ipmi-fan-control -fsystemctl stop restores Dell's automatic fan control.
TrueNAS has no persistent /usr/local/bin and no user systemd units. Put the
script on a dataset, then add a Post-Init script under System Settings >
Advanced > Init/Shutdown Scripts, type Command:
/mnt/pool/scripts/fan-control.sh &
The loop schedules itself, so no cron entry is needed.
Everything lives in /etc/dell-ipmi-fan-control.conf (or point
FAN_CONTROL_CONFIG elsewhere). See
fan-control.conf.example.
INTERVAL=30 # seconds between readings
HYSTERESIS=2 # degrees C buffer before stepping fans down
SENSOR_NAME="Temp" # from `list-sensors`
CURVE=(
"40:15" # temp_up:percent, ascending
"50:20"
"60:30"
"68:50"
"75:70"
"80:100"
)At each reading the highest tier whose temp_up the sensor meets is applied.
That curve is tuned for a single-socket 12G box and is a starting point, not a recommendation. Dual sockets or high-TDP chips will sit a tier or two higher at idle. Watch your own logs for a day and adjust rather than copying it verbatim.
To drive a Dell from another machine instead of running on the server itself:
IPMI_HOST="192.0.2.10"
IPMI_USER="root"
IPMI_PASS="calvin"Leave IPMI_HOST empty for local control. Needs "IPMI Over LAN" enabled in
iDRAC. The password reaches ipmitool through the environment, so it does not
show up in ps while the loop is running.
tail -f /var/log/fan-control.log # what it is doing
sudo systemctl stop dell-ipmi-fan-control # stop (restores auto)
kill "$(cat /var/run/fan-control.pid)" # ...if you started it by handFor anyone who would rather understand this than run it. These are the well-known Dell raw IPMI commands, and there is nothing proprietary here:
| Action | Command |
|---|---|
| Manual fan mode | raw 0x30 0x30 0x01 0x00 |
| Automatic fan mode | raw 0x30 0x30 0x01 0x01 |
Set fan speed (NN = hex %) |
raw 0x30 0x30 0x02 0xff 0xNN |
The daemon is a loop around those three plus a sensor read. If the commands were all you wanted, take them and skip the rest. What you would be reimplementing is the hysteresis, the failsafe, and the preflight.
Agent skills: unifi · home-assistant · batocera · psn · arr-stack
Retro cabinet: batocera-toolbox · batocera-holidays
Home server: plex-preroll-roulette
PlayStation: awesome-psnstats
Desktop: fastfetch-macos-gradient-hud
MIT. See LICENSE.
Not affiliated with Dell. "PowerEdge" and "iDRAC" are used descriptively.