Artesyn System Management Interface Based on HPI-B (Centellis CO 31kX-4100-2000-4410) (June 2014) - Manual (Page 74)

Using HPI-B
System Management Interface Based on HPI-B (Centellis CO31kX/4100/2000/4410) User’s Guide 74
4.5.1 Cooling Management Performed by ATCA-
M100/MF105/SAM1410
Cooling management as performed by the ATCA-M100/MF105/SAM1410 HPI daemon
software includes the monitoring of operating temperatures within a shelf, and depending on
the data obtained, controlling the cooling fans in order to ensure proper cooling of all
components in a shelf. Apart from proper cooling, another important goal of cooling
management is to keep the noise caused by the fans to a minimum. This is important to meet
NEBS requirements.
4.5.1.1 Basic Functionality
For the cooling management, the software considers all IPMI temperature sensors in the shelf.
This includes sensors on FRUs, such as blades and AMC modules, but also inlet/outlet sensors
of the shelf. The latter are combined to a single virtual difference sensor.
After system start-up, the fans are operated at minimum speed and the shelf management
software starts to monitor all temperature sensors.
As soon as a sensor reaches or exceeds the upper minor threshold, the software initializes and
starts a virtual Proportional-Integral-Derivative (PID) controller for the respective sensor. The
PID uses the current sensor temperature as input and the fan control level as output. In the case
of the virtual difference sensor, the input is a predefined air difference temperature profile. The
algorithm used within the PID keeps the measured temperature at the upper minor threshold.
If more than one sensor has reached the temperature warning level and therefore several PIDs
are active at the same time, the software combines the several outputs of the PIDs into one
output which is used to control the fans.
Whenever one or more temperature sensors have reached the upper non-recoverable level,
the fan speed is always set to the maximum, i.e. 100%.
Whenever one or more sensors have reached the upper critical level, the software increases
the fan speed by a certain percentage, calculated by an internal algorithm. This can typically
be observed as a sudden increase of the fan noise.