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Chapter 4. BMC Configuration Settings
J4078-01 User Manual
How to manually change PWM (fan speed) for all Cooling elements
Cooling control element
BYTE/BIT
7
6
5
4
3
2
1
0
0
COMMON CONTROL
SELECT PRDFAIL DISABLE
RST
SWAP
Reserved
1
RQST
IDENT
Reserved
2
Reserved
3
Reserved RQST
FAIL
RQST ON
Reserved
REQUESTED SPEED CODE
The "RQST IDENT" for Cooling is defined in the bit7, byte1 and the "REQUESTED SPEED
CODE" is defined in the bit2 ~ 0, byte3 of the "Cooling control element" in the SES
specification. Set "RQST IDENT" bit to disable the smart fan function, and then change
PWM or fan speed for all Cooling elements by setting the "REQUESTED SPEED CODE" bits.
Clear "RQST IDENT" bit to enable the smart fan function again. Please disable the smart fan
function before changing PWM or fan speed. Only the first Cooling element of each type (HUB
fans and System fans) supports this feature. We use the software package "sg3_utils" on
Linux for example, and have a SAS HBA and a cable to connect your host with the expander.
(A) Show the device for AIC Expander Controller (canister)
$ sg_map -i
/dev/sg2 AIC 12G 4U78swapHub 0c30
(B) Set "RQST IDENT" of the first Cooling element to disable the smart fan function
“HubCoolingElement00” is the first cooling element for the HUB / motherboard, and
“SysCoolingElement00” is the first cooling element for the HDDs / backplane. Here we
take “SysCoolingElement00” as example.
$ sg_ses --descriptor= SysCoolingElement00 --set=1:7:1 /dev/sg2
(C) Set "REQUESTED SPEED CODE" of SysCoolingElement00 to change PWM or fan speed
for all Cooling elements. Set "REQUESTED SPEED CODE"=7 (100% PWM) for example.
$ sg_ses --descriptor= SysCoolingElement00 --set 3:2:3=7 /dev/sg2
