Bmc Service Processor - IBM 88743BU - System x3950 E User Manual

1.12.2 BMC service processor

The baseboard management controller (BMC) is a small, independent controller
that performs low-level system monitoring and control functions, and interface
functions with the remote Intelligent Platform Management Interface (IPMI). The
BMC 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 LEDs on the Light Path Diagnostics panel to help you diagnose
the problem. It also records the error in the BMC system event log.
The BMC functions are as follows:
Initial system check when AC power is applied
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 nonvolatile
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
The BMC monitors the system and reports when the BIOS and POST phases
are complete and the operating system has booted.
System event monitoring
During run time, the BMC continually monitors critical system items such as
fans, power supplies, temperatures, and voltages. The system status is
logged and reported to the service processor, if present.
System fan speed control
The BMC monitors system temperatures and adjusts fan speed accordingly.
We describe more about the BMC in 6.1, "BMC configuration options" on
page 300.
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Planning, Installing, and Managing the IBM System x3950 M2