IBM 71413SU Technical Reference - Page 36

Power-control button/power-on LED Ethernet icon LED 1 2 Information LED System-error LED NMI button (trained service technician only) Power-control button cover Ethernet port activity LEDs Locator button/ locator LED REMIND OVER SPEC LOG LINK PS PCI SP FAN TEMP MEM NMI CNFG CPU VRM DASD RAID BRD Light Path Diagnostics 1 2 3 4 Figure 17 Light path diagnostic panel Baseboard Management service processor The Baseboard Management Controller (BMC) is a small, independent micro-controller used to perform low-level system monitoring and control functions, as well as remote IPMI interface functions. It uses multiple I2C bus connections to communicate out-of-band with other onboard devices. The BMC provides environmental monitoring for the server. If environmental conditions exceed thresholds or if system components fail, the BMC lights the light path diagnostic LEDs to help you diagnose the problem and also records the error in the BMC system event log. BMC functions are as follows: Initial system check at A/C on The BMC monitors critical I2C devices in standby power mode to determine if the system configuration is safe for power-on. BMC Event log maintenance The BMC maintains and updates an IPMI-specified event log in non-volatile storage. Critical system information is recorded and made available for external viewing. System power state tracking The BMC monitors the system power state and logs transitions into the system event log. System initialization The BMC has I2C access to certain system components that might require initialization before power-up. System software state tracking 36 IBM System x3950 M2 and x3850 M2 Technical Introduction