Kontron AM4901 IPMI - Manual (Page 19)

AM5901/AM4901 IPMI Firmware User Guide
ID: 1035-8760, Rev. 3.0 Page 19
Normally the fan control foresees 16 different fan speed levels (0 to 15 = 0 to F in CLI com-
mand). There are, however, systems whose fans can only be on or off. This can lead to a very
coarse regulation and it could be advisable to deactivate the fan control and let the fan(s) op-
erate at their own fixed speed.
Please note: For OM6060 systems there is the restriction that the fan is only capable of being
switched on or off. If the calculated fan speed level is <= 3 the fan will be switched off, otherwise
the fan will run at full speed.
3.4.1 Regulation Parameters
The following temperature regulation parameters are available. Input and output to the com-
mand line is done via the CLI command “tcp” without “0x” or “h” affixed. The default values are
in parenthesis, time is in seconds.
• initialFanLevel (8)
• minFanLevel (3)
• coolingFanIncreaseTimeout (3c = decimal 60)
• coolingFanDecreaseTimeout (3c = decimal 60)
• fanLevelStepUp (2)
• fanLevelStepDown (1)
• normalStableTime (708 = decimal 1800)
3.4.2 Regulation Algorithm
The MCH registers critical as well as non-critical temperature events within the system. There
are three possible states which are registered:
• State 0 = no active temperature event
• State 1 = at least one non-critical temperature event is active
• State 2 = at least one critical temperature event is active
The MCH always starts in the state 0 and with the fan speed “initialFanLevel”.
In state 0, the fan speed is then reduced by the value of “fanLevelStepDown” after
“coolingFanDecreaseTimeout” seconds until the level “minFanLevel” is achieved. After further
“normalStableTime” seconds, the “minFanLevel” is decreased by one level with a
corresponding reduction in fan speed.
Transition from state 0 to state 1 results in the immediate increase of “minFanLevel” and the
fan speed by the level “fanLevelStepUp”. Following this, the fan speed will be increased by “fan-
LevelStepUp” every “coolingFanIncreaseTimeout” seconds until either state 0 or state 2 oc-
curs.
By a transition to state 2, the fan speed increases immediately to the maximum possible speed
and remains there until the system transitions to state 0.