Sun Microsystems Sun Fire V490 - Manual (Page 48)

20 Sun Fire V490 Server Administration Guide • August 2004
Power Supply Redundancy
The system features two hot-swappable power supplies, either of which is capable of
handling the system’s entire load. Thus, the system provides N+1 redundancy,
allowing the system to continue operating should one of the power supplies or its
AC power source fail. For more information about power supplies, redundancy, and
configuration rules, see “About the Power Supplies” on page 38.
Environmental Monitoring and Control
The Sun Fire V490 system features an environmental monitoring subsystem
designed to protect against:
■ Extreme temperatures
■
Lack of adequate airflow through the system
■
Power supply failures
Monitoring and control capabilities reside at the operating system level as well as in
the system’s Boot PROM firmware. This ensures that monitoring capabilities remain
operational even if the system has halted or is unable to boot.
The environmental monitoring subsystem uses an industry-standard Inter-
Integrated Circuit (I
2 C) bus. The I 2 C bus is a simple two-wire serial bus, used
throughout the system to allow the monitoring and control of temperature sensors,
fans, power supplies, status LEDs, and the front panel system control switch.
Temperature sensors are located throughout the system to monitor the ambient
temperature of the system and the temperature of several application-specific
integrated circuits (ASICs). The monitoring subsystem polls each sensor and uses
the sampled temperatures to report and respond to any overtemperature or
undertemperature conditions.
The hardware and software together ensure that the temperatures within the
enclosure do not stray outside predetermined “safe operation” ranges. If the
temperature observed by a sensor falls below a low-temperature warning threshold
or rises above a high-temperature warning threshold, the monitoring subsystem
software lights the system Fault LED on the front status and control panel.
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.
The monitoring subsystem is also designed to detect fan failures. The system
features two fan trays, which include a total of five individual fans. If any fan fails,
the monitoring subsystem detects the failure and generates an error message and
logs it in the /var/adm/messages file, lights the appropriate fan tray LED, and
lights the system Fault LED.