Intel® Server Board S2600CW Platform Management
Intel® Server Board S2600CW Family TPS
76
Revision 2.4
implements fan presence sensors for each hot-swappable fan. These are instantiated as IPMI
discrete sensors.
Events are only logged for fan presence upon changes in the presence state after AC power is
applied (no events logged for initial state).
5.3.13.3
Fan Redundancy Sensor
The BMC supports redundant fan monitoring and implements fan redundancy sensors for
products that have redundant fans. Support for redundant fans is chassis-specific.
A fan redundancy sensor generates events when its associated set of fans transitions between
redundant and non-redundant states, as determined by the number and health of the
component fans. The definition of fan redundancy is configuration dependent. The BMC
allows redundancy to be configured on a per fan-redundancy sensor basis through OEM SDR
records.
There is a fan redundancy sensor implemented for each redundant group of fans in the
system. Assertion and de-assertion event generation is enabled for each redundancy state.
5.3.13.4
Power Supply Fan Sensors
Monitoring is implemented through IPMI discrete sensors, one for each power supply fan. The
BMC polls each installed power supply using the PMBus* fan status commands to check for
failure conditions for the power supply fans. The BMC asserts the “performance lags” offset of
the IPMI sensor if a fan failure is detected.
Power supply fan sensors are implemented as manual re-arm sensors because a failure
condition can result in boosting of the fans. This in turn may cause a failing fan’s speed to rise
above the “fault” threshold and can result in fan oscillations. As a result, these sensors do not
auto-rearm when the fault condition goes away but rather are rearmed only when the system
is reset or power-cycled, or the PSU is removed and replaced with the same or another PSU.
After the sensor is rearmed, if the fan is no longer showing a failed state, the failure condition
in the IPMI sensor shall be cleared and a de-assertion event shall be logged.
5.3.13.5
Monitoring for “Fans Off” Scenario
On Intel® Server Systems supporting the Intel® Xeon® processor E5-2600 v3 and v4 product
families, it is likely that there will be situations where specific fans are turned off based on
current system conditions. BMC Fan monitoring will comprehend this scenario and not log
false failure events. The recommended method is for the BMC FW to halt updates to the value
of the associated fan tach sensor and set that sensor’s IPMI sensor state to “reading-state-
unavailable” when this mode is active. Management software must comprehend this state for
fan tach sensors and not report these as failure conditions.
The scenario for which this occurs is that the BMC Fan Speed Control (FSC) code turns off the
fans by setting the PWM for the domain to 0. This is done when based on one or more global
aggregate thermal margin sensor readings dropping below a specified threshold.