HP Integrity rx8620 Server User Service Guide

System Backplane to Core I/O Card Connectivity
The core I/O card connectors are right-angle connectors that mate with the system backplane.
Three connectors per core I/O card carry one PCI bus from the system to the core I/O board and
three single-ended SCSI busses from the core I/O to the system backplane. The system backplane
contains two LBA PCI bus controllers, one per core I/O board, and six 68-pin SCSI connectors
(three per core I/O board).
The LBA PCI bus controllers are placed on the system backplane to facilitate removal of the core
I/O cards when standby power is on. The partition for the core I/O card must be shut down
before removing the card.
Placement of the SCSI connectors on the system backplane also permits removal of a core I/O
card without having to remove cables in the process. Hot-plug circuitry is located near the system
backplane/core I/O card mating area.
System Backplane to PCI-X Backplane Connectivity
The PCI-X backplane uses two connectors for the SBA link bus and two connectors for the
high-speed data signals and the manageability signals.
SBA link bus signals are routed through the system backplane to the cell controller on each
corresponding cell board.
The high-speed data signals are routed from the SBA chips on the PCI-X backplane to the two
LBA PCI bus controllers on the system backplane.
Clocks and Reset
The system backplane contains reset and clock circuitry that propagates through the whole
system. The system backplane central clocks drive all major chip set clocks.
I/O Subsystem
The cell board to the PCI-X board path runs from the CC to the SBA, from the SBA to the ropes,
from the ropes to the LBA, and from the LBA to the PCI slots seen in Figure 1-11. The CC on cell
board 0 and cell board 1 communicates through an SBA over the SBA link. The SBA link consists
of both an inbound and an outbound link with an effective bandwidth of approximately 1 GB
per second. The SBA converts the SBA link protocol into ropes. A rope is defined as a high-speed,
point-to-point data bus. The SBA can support up to 16 of these high-speed bi-directional rope
links for a total aggregate bandwidth of approximately 4 GB per second. Each LBA acts as a bus
bridge, supporting either one or two ropes and capable of driving 33 MHz or 66 MHz for PCI
cards. The LBAs can also drive at 66 MHz or 133 MHz for PCI-X cards. When cell board 2 and
cell board 3 are present, the cell boards attach to their own associated SBA and LBA chips on the
PCI-X board in the Server Expansion Unit.
HP Integrity rx8620 Server Block Diagram 27