Cooling Options for Thermal Control in Dell [600853]

Cooling Options for Thermal Control in Dell
PowerEdge Servers
Customize the cooling options for installed server hardware
Dell Product Group | Server Engineering
January 2015

2 Cooling Options for Thermal Control in Dell PowerEdge Servers
Table of contents
Revisions ………………………….. ………………………….. ………………………….. ………………………….. ………………………….. ……………………….. 2
Acknowledgements ………………………….. ………………………….. ………………………….. ………………………….. ………………………….. ………. 2
PowerEdge server thermal control options ………………………….. ………………………….. ………………………….. ………………………….. . 3
Fan Offset option ………………………….. ………………………….. ………………………….. ………………………….. ………………………….. ……. 3
Minimum Fan Speed (MFS) option ………………………….. ………………………….. ………………………….. ………………………….. ………. 4
Combining Fan Offset and MFS settings ………………………….. ………………………….. ………………………….. …………………………. 5
Maximum Exhaust Temperature option ………………………….. ………………………….. ………………………….. ………………………….. 6
Customizing the thermal settings on a PowerEdge server ………………………….. ………………………….. ………………………….. ……. 7
Customizing fan speed using HII ………………………….. ………………………….. ………………………….. ………………………….. ………… 8
Customizing fan speed using iDRAC WebGUI ………………………….. ………………………….. ………………………….. ……………….. 11
Customizing fan speed using RACADM ………………………….. ………………………….. ………………………….. …………………………. 13

Revisions
Date Description
January 2015 Initial release

Acknowledgements

This paper was produced by the Server Engineering Team.
Autho rs: Hasnain Shabbir and Dominick Lovicott

This document is for informational purposes only and may contain typographical errors and technical inaccuracies.
The content is provided as is, without express or implied warranties of any kind.

© 201 5 Dell Inc. All rights reserved. Reproduction of this mate rial in any manner whatsoever without the express
written permission of Dell Inc. is strictly forbidden. For more information, contact Dell. Dell, the DELL logo, and the
DELL badge are trademarks of Dell Inc. Other trademarks and trade names may be used in this document to refer to
either the entities claiming the marks and names or their products. Dell disclaims any proprietary interest in the marks
and names of others.

3 Cooling Options for Thermal Control in Dell PowerEdge Servers
PowerEdge server thermal control options
Dell PowerEdge servers include proprietary thermal controls that automatically manage server component
temperatures . These controls utilize sensor monitoring and information about hardware that is installed to
minimize fan speeds , airflow, and power consumption without sacrificing reliability.
Adjusting the thermal controls i n a PowerEdge server can be helpful if your server has a third -party PCIe
card that needs additional cooling other than the default settings . Another example may be that the
exhaust temperature of a server is too high for the switch mounted behind the server. In both cases, you
would want to customize the fan control settings as described in this best practices guide .
This guide describe s the fan control options and suggest s some potential usages. Although these controls
allow for customization of cooling, the server will never allow speeds to go below the threshold that is
required to cool the server and any ada pters provided by Dell. These options apply only to server system
fans and do not influence fans located in peripheral devices such as power supplies or PCIe cards.
Fan Offset option

With t he Fan Offset option you can increase the system fan speed in four incremental steps.
 Low Fan Speed — Increases fan speeds by a low amount
 Medium Fan Speed — Increases fan speeds by a moderate amount
 High Fan Speed — Increases fan speeds by a large amount
 Max Fan Speed — Increases fan speeds to full speed
 Off (Default) — Baseline fan speed is applied with no offset

Note : Increasing the server fan speed to reduce component temperature and increase airflow will also
increase server power consumption.
These settings add a predefined amount of fan speed to the b aseline established by the automatic controls
and are equally divided between the typical baseline and the ma ximum speed of the server fans. The
automatic controls continue to maintain component temperatures based on sensor readings that may
increase fan s peeds beyond the user defined offset .
The fan speed offset increases all fan speeds by the same percentage . Some hardware configurations that
have higher baseline fan speeds will have lower offsets for reaching the maximum speed. The amount of
cooling provided by an offset and the percent increase in speed var ies by server model .
Adjusting the Fan Offset setting can improve system cooling if your server has a third -party PCIe card
adapter installed . However, the feature can be used to increase system c ooling for other purposes. Figure
1 illustrat es how the fan speed offset ( shown in b lue) increases the fan speed above the baseline ( shown in
grey).

4 Cooling Options for Thermal Control in Dell PowerEdge Servers

Figure 1 Fan speed of fset
Minimum Fan Speed (MFS) option

The Minimum Fan Speed option lets you set a baseline that the fan speed cannot go below . This setting is
defined granularly as a percentage of the fan speed range (or % PWM) .
System fans can run higher than the fan speed set by the MFS option (unless set to 100%), but not lower.
For example, setting MFS at 35% limits the fan speed to never go lower than 35% PWM.
Note : 0% PWM does not mean the fan is off , but means i t is the lo west fan speed available .
Figure 2 illustrates how the MFS setting works in conjunction with the automatic controls.
Note: Other subsystems in a server , like the CPU, may require fan speeds higher than the MFS or
automatic baseline. This will generally occur during moderate to high usage of the computing subsystem.

5 Cooling Options for Thermal Control in Dell PowerEdge Servers

Figure 2 Illustrat es how the Minimum Fan Speed setting creates a fan speed floor or lower bound
Combin ing Fan Offset and MFS settings
Fan Offset and MFS options can be us ed together for a combined result. Figure 3 highlights how the fan
offset and MFS might be used togethe r to achieve a desired result.

Figure 3 Illustrat es how options can be combined

6 Cooling Options for Thermal Control in Dell PowerEdge Servers
Maximum Exhaust Temperature option

The Maximum Exhaust Temperature option allows the system fan speeds to be regulated to prevent the
system exhaust air temperature from exceeding the chosen threshold . Two important things to note
regarding this option:
1. Maintaining the desired exhaust temperature cannot be guaranteed und er all conditions. For example ,
if a system with a rich configuration of components is operating under full utilization and operating in
a high ambient temperature environment , the system may not have enough cooling headroom to
maintain a low exhaust tempe rature. The default value is 70°C (158 °F), and will be maintained under
all conditions.
2. It is also possible that there may not be any changes to the fan speed as a result of this setting if the
system configuration, inlet ambient conditions , and server wo rkload do not have a higher exhaust
ambient temperature than the desired setting.
All of the custom fan speed options are persistent, which means that once they are set and applied, they
do not automatically change to the default setting during system rebo ot, power cycling, iDRAC, or BIOS
updates. A few Dell servers may or may not support some or all of these custom user -cooling options. If
the options are not supported, they are not displayed or you cannot provide a custom value.

Figure 4 llustrates how airflow i ncreases to maintain an exhaust temperature limit

7 Cooling Options for Thermal Control in Dell PowerEdge Servers
Customizing the thermal settings on a PowerEdge server
There are a number of user interfaces available for customizing the fan speed settings in a PowerEdge
server . The f ollowing is a brief summary of the se interfaces.
 iDRAC GUI
– Web browser based
– Requires network connection (Note: Alternate access via USB A -A cable also possible)
– GUI based and easy to navigate
– No reboot required
 HII (Human Interface Infrastructure) browser
– Accessed through BIOS Setup (F2)
– Does not require network connection since setup is done directly on the server through BIOS
setup
 IPMI (Intelligent Platform Management Interface)
 WSMAN (Web Service Management)
 RACADM (Remote Access Controller Admin)
– Requires network connection and remote access to the server
Figure 5 illustrates user interaction with a server using the various interfaces.

Figure 5 Illustrates the user paths for chang ing thermal settings

8 Cooling Options for Thermal Control in Dell PowerEdge Servers
Custom izing fan speed using HII
To access the iDRAC Settings options (BIOS setup screen ), press F2 at boot , then select iDRAC Settings . To
customize thermal settings, select Thermal .

Figure 6 iDRAC Settings – Thermal

Figure 7 iDRAC Settings – User Cooling Options

9 Cooling Options for Thermal Control in Dell PowerEdge Servers

Figure 8 Setting Max Exhaust Temperature Limit

Figure 9 Setting Fan Speed Offset

Figure 10 Setting Minimum Fan Speed (MFS)
In addition to the custom cooling option s, you can change the System Thermal Profile to either maximize
performance or power efficiency. The Thermal Profile settings determine the Automatic Baseline.

10 Cooling Options for Thermal Control in Dell PowerEdge Servers

Figure 11 Setting System Thermal Profile
The System Thermal Profile provides the following options :
 Default Thermal Profile Settings:
– Indicates that thermal algorithm uses the same System Profile setting that is defined under
System BIOS Settings > System Profile Settings in System BIOS menu
– Selecting any other option (Maximum Performance or Minimum Power) overrides thermal
settings associated to System Profile setting under System BIOS Settings > System Profile
 Maximum Performance:
– Reduced probability of memory or CPU throttling
– Increased proba bility of turbo mode activation
– Generally higher fan speeds at idle as well as stress loads
 Minimum Power:
– Optimized for lowest system power consumption based on optimum fan power state
– Generally lower fan speeds at idle as well as stress loads

11 Cooling Options for Thermal Control in Dell PowerEdge Servers
Custom izing fan speed using iDRAC WebGUI

iDRAC WebGUI is a GUI -based web management interface you can use to custom ize server fan settings.
You can connect to a server iDRAC WebGUI with an IP address on a remote web browser.

Figure 12 iDRAC WebGUI
Click Fans in Server Health or in Hardware section in the left pane to open the Fan Status page.

Figure 13 Accessing the Fan Status page

12 Cooling Options for Thermal Control in Dell PowerEdge Servers
The Fan Status page provides a snapshot of information about the fans in your system.

Figure 14 Fan Configuration information
The Fan Configuration section shows the current settings in the Value column .
To customize the fan speed settings, c lick Setup and use the dropdown menus to make setting changes .

Figure 15 Fan Setup options

13 Cooling Options for Thermal Control in Dell PowerEdge Servers

Figure 16 Setting Maximum Exhaust Temperature Limit
Custom izing fan speed using RACADM

After logging into iDRAC, run "racadm get system.thermalsettings" to display the current settings.
Example result:
~ # racadm get system.thermalsettings
[Key=system.Embedded.1#ThermalSettings.1]
AirExhaustTemp=70
#FanSpeedHighOffsetVal=71
#FanSpeedLowOffsetVal=24
#FanSpeedMaxOffsetVal=100
#FanSpeedMediumOffsetVal=48
FanSpeedOffset=Off
#MFSMaximumLimit=100
#MFSMinimumLimit=0
MinimumFanSpeed=255
ThermalProfile=Default Thermal Profile Settings
~ #

Use Table 1 as a guide for configuring these settings using the racadm system.thermalsettings command .
Table 1 RACADM SYSTEM.THERMALSETTINGS command options
Object Description Usage Example
AirExhaustTemp  Max Air Exhaust
Temperature limit
setting;
 Set Exhaust
Temperature Limit to
any one value
(platform depended),
where 0,1,2,3,4 and
255 corresponds to
40,45,50,55,60 deg C Values from 0 -4
and 255 (default) To check existing setting on the system:
racadm get
system.thermalsettings.AirExhaustTemp
It will report: AirExhaustTemp=70
This means that system is set to limit air
exhaust temperature to 70C.

To set exhaust temperature limit to 60C:
racadm s et
Command
Response

14 Cooling Options for Thermal Control in Dell PowerEdge Servers
Object Description Usage Example
and 70C deg C
(default).
system.thermalsettings.AirExhaustTemp 4
Result will be “Object value modified
successfully“ and 60C exhaust limit is set.

If certain AirExhaust Temperature limit is not
supported by platform (e.g. 40C), then
running that command:
racadm set
system.ther malsettings.AirExhaustTemp 0
Will result in error:
ERROR: RAC947: Invalid object value
specified.
Make sure to specify the value depending
on the type of object.
For more information, see RACADM help.

To set the limit to default value:
racadm set
system.thermalsettings.AirExhaustTemp 255
FanSpeedHighOffsetVal  Getting this variable will
read the fan speed
offset value in %PWM
for High Fan Speed
Offset setting.
 This value is platform
dependent
 Use FanSpeedOffset to
set this value using
index value 1 Values from 0 -100 racadm get system.thermalsettings
FanSpeedHighOffsetVal

This will return a value like “66” meaning
that when you use command
“racadm set system.thermalsettings
FanSpeedOffset 1”, it will apply a fan speed
offset of High (66% PWM) over baseline fan
speed
FanSpeedLowOffsetVal  Getting this variable will
read the fan speed
offset value in %PWM
for Low Fan Speed
Offset setting.
 This value is platform
dependent
 Use FanSpeedOffset to
set this value using
index value 0 Values from 0 -100 racadm get system.thermalsettings
FanSpeedLowOffsetVal

This will return a value like “23” meaning
that when you use command
“racadm set system.thermalsettings
FanSpeedOffset 0”, it will apply a fan speed
offset of Low (23% PWM) over baseline fan
speed
FanSpeedMaxOffsetVal  Getting this variable will
read the fan speed
offset value in %PWM
for Max Fan Speed
Offset setting
 This value is platform
dependent
 Use FanSpeedOffset to
set this value using
index value 3 Values from 0 -100 racadm get system.thermalse ttings
FanSpeedMaxOffsetVal

This will return a value like “100” meaning
that when you use command
“racadm set system.thermalsettings
FanSpeedOffset 3”, it will apply a fan speed
offset of Max (meaning full speed, 100%
PWM). In most cases, this offset will result in
fan speeds going to full speed.
FanSpeedMediumOffsetVal  Getting this variable will
read the fan speed Values from 0 -100 racadm get system.thermalsettings

15 Cooling Options for Thermal Control in Dell PowerEdge Servers
Object Description Usage Example
offset value in %PWM
for Medium Fan Speed
Offset setting
 This value is platform
dependent
 Use FanSpeedOffset to
set this value using
index value 2 FanSpeedMediumOffsetVal

This will return a value (for example) “47”
meaning that when you use command
“racadm set system.thermalsettings
FanSpeedOffset 2”, it will apply a fan speed
offset of Med ium (47% PWM) over baseline
fan speed
FanSpeedOffset  Using this with “get” will
report the existing Fan
Speed Offset setting
 Using this with “set” will
allow setting the
desired fan speed offset
value based.
 The index will govern
what offset is applied
and FanSpeed…Val
variables (defined
earlier) will be the
values at which the
offsets will be applied 0-Low Fan Speed,
1-High Fan
Speed,2 -Medium
Fan Speed,3 -Max
Fan Speed,255 –
None Example with get:
racadm get
system.thermalsettings.FanSpeedOffset

will repo rt current setting.

Example with set:
racadm set
system.thermalsettings.FanSpeedOffset 1

will result in fan speed offset set to High
value (as defined in
“FanSpeedHighOffsetVal”)
MFSMaximumLimit  Read Maximum limit for
MFS Values from 1 –
100; Default – 255
(meaning None) racadm get
system.thermalsettings.MFSMaximumLimit

Will report the highest value that can be set
using MinimumFanSpeed option
MFSMinimumLimit  Read Minimum limit for
MFS Values from 0 –
MFSMaximumLimit
; Default – 255
(meaning None) racadm get
system.thermalsettings.MFSMinimumLimit

Will report the lowest value that can be set
using MinimumFanSpeed option
MinimumFanSpeed  Allows configuring of
Minimum Fan speed
that is desired for the
system to operate
 It defines the baseline
(floor) value for fan
speed and system will
allow fans to go below
this defined fan speed
value
 This value is %PWM
value for fan speed Values from
MFSMinimumLimit
to
MFSMaximumLimit

When get
command reports
255, it means no
user configured
offset applied racadm set
system.thermalsettings.MinimumFanSpeed
45

Will force the system minimum speed to not
go below 45% PWM (45 should be a value
between what is read from
MFSMinimumLimit to MFSMaximumLimit)
ThermalProfile  Selection for Thermal
Base Algorithm
 Allows syste m profile to
be set at desired setting
for thermal behavior
associated to the profile 0-Auto, 1 –
Maximum
performance, 2 –
Minimum Power Example using get:
racadm get
system.thermalsettings.ThermalProfile

will report the current ThermalProfile setting

16 Cooling Options for Thermal Control in Dell PowerEdge Servers
Object Description Usage Example
Example using set:
Racadm set
system.thermalsettings.ThermalProfile 1

Will result in Thermal Profile to be set to
Maximum Performance Mode.