Installation guide

22 IBM Eserver xSeries 366 Technical Introduction
Figure 12 Light path diagnostic panel
Baseboard Management Controller 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 it 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.
Power-control
button
Power-on LED
USB connector
Hard disk
drive activity
Information
LED
System
error
Locator LED
Release latch - slide to the left
and pull out to display the light
path diagnostics panel
DASD
NMI
PCI
BRD
I/O
BRD
PS
NONRED
SP
LINK
RAID
MEM
CPU
CPU
BRD
FAN
PCI
VRM
OVER SPEC
TEMP
REMIND
LOG
Light Path
Diagnostics