Environmental Monitoring And Control - Sun Microsystems Sun Fire V445 Server Administration Manual

Environmental Monitoring and Control

The Sun Fire V445 server features an environmental monitoring subsystem that
protects the server and its components against:
Extreme temperatures
Lack of adequate airflow through the system
Operating with missing or misconfigured components
Power supply failures
Internal hardware faults
Monitoring and control capabilities are handled by the ALOM system controller
firmware. This ensures that monitoring capabilities remain operational even if the
system has halted or is unable to boot, and without requiring the system to dedicate
CPU and memory resources to monitor itself. If the ALOM system controller fails,
the operating system reports the failure and takes over limited environmental
monitoring and control functions.
The environmental monitoring subsystem uses an industry-standard I
2
I C bus is a simple two-wire serial bus used throughout the system to allow the
monitoring and control of temperature sensors, fan trays, power supplies, and status
indicators.
Temperature sensors are located throughout the system to monitor the ambient
temperature of the system, the CPUs, and the CPU die temperature. The monitoring
subsystem polls each sensor and uses the sampled temperatures to report and
respond to any overtemperature or undertemperature conditions. Additional I
sensors detect component presence and component faults.
The hardware and software together ensure that the temperatures within the
enclosure do not exceed 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 Service Required indicators on the front and back panels. If the
temperature condition persists and reaches a critical threshold, the system initiates a
graceful system shutdown. In the event of a failure of the ALOM system controller,
backup sensors are used to protect the system from serious damage, by initiating a
forced hardware shutdown.
All error and warning messages are sent to the system console and logged in the
/var/adm/messages file. Service Required indicators 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 integral power supply fan trays, and six fan trays each containing one fan.
Four fans are for cooling CPU/Memory modules and two fans are for cooling the
disk drive. All fans are hot-swappable. If any fan fails, the monitoring subsystem
100 Sun Fire V445 Server Administration Guide • September 2007
2 C bus. The
2
C