Environmental Monitoring And Control - Sun Microsystems Ultra Enterprise 450 Owner's Manual

Environmental Monitoring and Control

The system features an environmental monitoring subsystem designed to protect
against:
Extreme temperatures
Lack of air flow through the system
Power supply problems
Monitoring and control capabilities reside at the operating system level as well as in
the system's flash PROM firmware. This ensures that monitoring capabilities are
operational even if the system has halted or is unable to boot.
The environmental monitoring subsystem uses an industry standard I
implemented on the main logic board. The I
used throughout the system to allow the monitoring and control of temperature
sensors, fans, power supplies, and status LEDs.
Temperature sensors (thermistors) are located throughout the system to monitor
each CPU module and power supply, as well as the ambient temperature of the
system. The monitoring subsystem frequently polls each thermistor in the system
and uses the sampled temperatures to:
Regulate fan speeds for maintaining an optimum balance between proper cooling
and noise levels.
Report and respond to any over temperature conditions.
To indicate an over temperature condition, the monitoring subsystem generates a
warning or error message, and depending on the nature of the condition, may even
shut down the system. If a CPU module reaches 80 degrees C or the ambient
temperature reaches 50 degrees C, the system generates a warning message,
illuminates the temperature fault LED on the status and control panel, and
automatically shuts itself down. In the case of a power supply, a warning is
generated when the power supply temperature reaches 95 degrees C and the system
is shut down if the temperature reaches 100 degrees C.
All error and warning messages are displayed on the system console (if one is
attached) and are logged in the /var/adm/messages file. Front panel fault LEDs
remain lit after an automatic system shut down to aid in problem diagnosis.
The monitoring subsystem is designed to protect the system from overheating even
if the operating system is hung. The system uses a timer that is continually reset by
the operating system. If the operating system fails to reset the timer within three
minutes, the system automatically accelerates all fans to full speed. The fans
spinning at full speed also provide an audible warning that the system is not
functioning properly.
46 Ultra Enterprise 450 Server Owner's Guide • July 1997
2
C bus is a simple two-wire serial bus,
2
C bus