Dell R720xd fan speed control

I run R720xd in my home lab setup. The very first thing was to resolve fan speed crisis, as default +16k rpm results in unlivable conditions.

This might also be suitable for other 12th-generation Dell PowerEdge servers, like:
T620, R220, R320, R420, R520, R620, R720, R820, R920, M420, M520, M620, M820, C6220.

This can be relatively easily achieved via IPMI control.
For this, you will need to set up IDRAC:

• Enable IDRAC passthrough to OS - This will allow you to connect to Idrac from within the operating system.
  Overview -> iDRAC Settings -> Network -> OS to iDRAC Pass-through enable USB NIC

• You should now have a new network interface in your operating system. For me, it was auto-detected and I did not need to tinker with it.

idrac: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 169.254.0.2  netmask 255.255.255.0  broadcast 169.254.0.255
        inet6 fe80::7a45:c4ff:fef4:1e56  prefixlen 64  scopeid 0x20<link>
        ether 78:45:c4:f4:1e:56  txqueuelen 1000  (Ethernet)
        RX packets 15861  bytes 8876316 (8.4 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 16563  bytes 5894357 (5.6 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

For fan control, you will need to send 2 commands,

• The first one is to enable manual fan control,
• The second is to set the fan speed.

• Setting fans to manual control:

ipmitool -I lanplus -H 169.254.0.1 -U root -P yourpasswordhere raw 0x30 0x30 0x01 0x00

• Set fan speed

ipmitool -I lanplus -H 169.254.0.1 -U root -P yourpasswordhere raw 0x30 0x30 0x02 0xff {FAN_SPEED_BYTE}

Where FAN_SPEED_BYTE is hex byte from 0x00 to 0x40 or decimal value from 0 to 64.

Example: Set the fan speed to value 16 (0x10 in hex) or about 10%

ipmitool -I lanplus -H 169.254.0.1 -U root -P yourpasswordhere raw 0x30 0x30 0x02 0xff 0x10

Example: Set the fan speed to 32 (0x20 in hex), or about 50%

ipmitool -I lanplus -H 169.254.0.1 -U root -P yourpasswordhere raw 0x30 0x30 0x02 0xff 0x20

In case of power loss, if your server is configured to boot up automatically, the default fan behavior will be re-enabled.

If you want to avoid these situations, you can set up automatic fan speed configuration on OS boot.

For this, I have a simple script /usr/local/bin/idrac-setfans :

#!/bin/bash

ipmitool -I lanplus -H 169.254.0.1 -U root -P yourpasswordhere raw 0x30 0x30 0x01 0x00 >/dev/null 2>&1
ipmitool -I lanplus -H 169.254.0.1 -U root -P yourpasswordhere raw 0x30 0x30 0x02 0xff 0x${1:-10} >/dev/null 2>&1

Note: This script takes in 1 parameter, whose value should be from 0 to 64.
For example: idrac-setfans 16

Add execute permission to this script

chmod +x /usr/local/bin/idrac-setfans

Set it to run once on boot by adding crontab entry on @reboot to any user.

@reboot /usr/local/bin/idrac-setfans 16

All done 🙂