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Platform Management Intel® Server Board SE7520JR2
Revision 1.0
C78844-002
118
5.1.4 Private Management Busses
A ‘Private Management Bus’ is a single-master I
2
C bus that is controlled by the management
controller. Access to any of the devices on the Private Management Bus is accomplished
indirectly via commands to the management controller via the IPMB or system interfaces.
Private Management busses are a common mechanism used for accessing temperature
sensors, system processor information, and other baseboard monitoring devices that are
located in various locations in the system.
The devices on the Private Management Bus are isolated from traffic on the IPMB. Since
devices such as temperature sensors are polled by the management controller, this gets the
polling traffic off the ‘public’ IPMB bus. This also increases the reliability of access to the
information, since issues with IPMB bus arbitration and message retries are avoided.
Furthermore, placing managed I
2
C devices on the private management bus frees up the I
2
C
addresses that those devices would have used up on the IPMB.
5.1.5 Management Controllers
At the heart of platform management is a management controller. To support the tiered
management model, the Server Board SE7520JR2 supports two different management
controllers, the PC87431M mini-Baseboard Management Controller (mBMC) from National
Semiconductor* and Intel’s Sahalee BMC. The Professional and Advanced modules electrically
replace the mBMC with the more full featured ‘Sahalee’ microcontroller. Sahalee is a custom
ARM7-TDMI based microcontroller designed for baseboard management applications on Intel
Server baseboards.
The management controller is a microcontroller that provides the intelligence at the heart of the
Intelligent Platform Management architecture. The primary purpose of the management
controller is to autonomously monitor system ‘sensors’ for system platform management events,
such as over-temperature, out-of-range voltages, etc., and log their occurrence in the non-
volatile System Event Log (SEL). This includes events such as over-temperature and over-
voltage conditions, fan failures, etc. The management controller also provides the interface to
the sensors and SEL so System Management Software can poll and retrieve the present status
of the platform. The contents of the log can be retrieved ‘post mortem’ in order provide failure
analysis information to field service personnel. It is also accessible by System Management
Software, such as Intel Server Management (ISM), running under the OS.
The management controller includes the ability to generate a selectable action, such as a
system power-off or reset, when a match occurs to one of a configurable set of events. This
capability is called Platform Event Filtering, or PEF.
The management controller includes ‘recovery control’ functions that allow local or remote
software to request actions such as power on/off, power cycle, and system hard resets, plus an
IPMI Watchdog Timer that can be used by BIOS andr run-time management software as a way
to detect software hangs.
The management controller provides ‘out-of-band’ remote management interfaces providing
access to the platform health, event log, and recovery control features via LAN (all tiers). IMM
based systems also allow access via serial/modem, IPMB, PCI SMBus, and ICMB interfaces.