IBM z13s, Technical Manual

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Chapter 4. Central processor complex I/O system structure
145
The I/O structure in a z13s CPC is shown in Figure 4-4. The PCIe switch card provides the
fanout from the high-speed x16 PCIe host bus to eight individual card slots. The PCIe switch
card is connected to the drawers through a single x16 PCIe Gen3 bus from a PCIe
fanout card.
In the PCIe I/O drawer, the eight I/O feature cards that directly attach to the switch card
constitute an I/O domain. The PCIe I/O drawer supports concurrent add and replace I/O
features to enable you to increase I/O capability as needed without having to plan ahead.
Figure 4-4 z13s (N20) connectivity to PCIe I/O drawers
The PCIe I/O Drawer supports up to 32 I/O features. They are organized into four hardware
I/O domains per drawer. Each I/O domain supports up to eight features and is driven through
a PCIe switch card. Two PCIe switch cards always provide a backup path for each other
through the passive connection in the PCIe I/O drawer backplane. During a PCIe fanout card
or cable failure, all 16 I/O cards in the two domains can be driven through a single PCIe
switch card.
As a RII design, a switch card in the front is connected to a switch card in the rear through the
PCIe I/O drawer board. Switch cards in same PCIe I/O drawer are connected to PCIe fanouts
across nodes, and CPC drawers for higher availability. This RII design provides a failover
capability during a PCIe fanout card failure or CPC drawer upgrade. All four domains in one of
these PCIe I/O drawers can be activated with four fanouts. The flexible service processors
(FSPs) are used for system control.
PCIe I/O Drawer
4GB/s PCIe
Gen2 x8
2GB/s PCIe
Gen2 x4
1GB/s PCIe
Gen1 x4
PU
PU PU
PU
Memory
PCIe Gen3
SC SC
CPC Drawer 0
PU
PU PU
PU
Memory
PCIe Gen3
SC SC
CPC Drawer 1
PCIe
Switch
PCIe Gen3
Interconnect
PCIe Gen3
Interconnect
PCIe Gen3
Interconnect
PCIe Gen3
Interconnect
2GB/s PCIe
Gen2 x4
2GB/s PCIe
Gen1 x8
FICON Express16S OSA Express5S
RII
RII
16GB/s PCIe Gen3
x16
FANOUTS
SMP
Cables
SMP
Cables