Supernodes - IBM Power Systems 775 Manual

System planar board
This section provides details about the following system planar board characteristics:
Approximately 2U x 85 cm wide x 131cm deep overall node package in 30 EIA frame
Eight octants and each octant features one QCM, one hub, and 4 - 16 DIMMs
128 memory slots
17 PCI adapter slots (octant 0 has three PCI slots, octant 1 - 7 each have two PCI slots)
Regulators on the bottom side of planar directly under modules to reduce loss and
decoupling capacitance
Water-cooled stiffener to cool regulators on bottom side of planar and memory DIMMs on
top of board
Connectors on rear of board to optional PCI cards (17x)
Connectors on front of board to redundant 2N DCCAs
Optical fiber D Link interface cables from HUB modules to left and right of rear tail stock
128 total = 16 links x 8 Hub Modules
Optical fiber L-remote interface cables from Hub modules to center of rear tail stock
96 total = 24 links x 8 Hub Modules
Clock distribution & out-of-band control distribution from DCCA.
Redundant service processor
The redundant service processor features the following characteristics:
The clocking source follows the topology of the service processor.
N+1 redundancy of the service processor and clock source logic use two inputs on each
processor and HUB chip.
Out-of-band signal distribution for memory subsystem (SuperNOVA chips) and PCI
express slots are consolidated to the standby powered pervasive unit on the processor
and HUB chips. PCI express is managed on the Hub and Bridge chips.

1.4.13 Supernodes

This section describes the concept of Supernodes.
Supernode configurations
The following supported Supernode configurations are used in a Power 775 system. The
usage of each type is based on cluster size or application requirements:
Four-drawer Supernode
The four-drawer Supernode is the most common Supernode configuration. This
configuration is formed by four CEC drawers (32 octants) connected via Hub optical links.
Single-drawer Supernode
In this configuration, each CEC drawer in the system is a Supernode.
Second level interconnect: L Remote
This level connects four CEC drawers (32 octants) together to create a Supernode via Hub
module optical links. Every octant in a node connects to every other octant in the other three
nodes in the Supernode. There are 384 connections in this level, as shown in Figure 1-18 on
page 31.
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