Sun Microsystems Enterprise 250 Owner's Manual page 60

For more information about RAID configurations, see "About Disk Array
Configurations and Concepts" on page 189.
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 are located throughout the system to monitor the ambient
temperature of the system and the temperature of each CPU module. The
monitoring subsystem frequently polls each sensor 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 message, and depending on the nature of the condition, may even shut
down the system. If a CPU module reaches 60 degrees C or the ambient temperature
reaches 53 degrees C, the system generates a warning message and illuminates the
temperature fault LED on the status and control panel. If a CPU module reaches 65
degrees C or the ambient temperature reaches 58 degrees C, the system is
automatically shut down.
This thermal shutdown capability is also built into the main logic board circuitry as
a fail-safe measure. This feature provides backup thermal protection in the unlikely
event that the environmental monitoring subsystem becomes disabled at both the
software and firmware levels.
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 shutdown to aid in problem diagnosis.
42 Sun Enterprise 250 Server Owner's Guide • June 1998
2
C bus is a simple two-wire serial bus,
2
C bus