IBM DS8000 manual RIO-G Interconnect, 263

complex, server 1. This affinity is established at creation of an extent pool. For details see Chapter 10, “The DS Storage Manager - logical configuration” on page 189.

Each single I/O enclosure itself contains six Fibre Channel adapters:

￿Two DAs which install in pairs

￿Four HAs which install as required

Each adapter itself contains four Fibre Channel ports.

Although each HA can communicate with each server, there is some potential to optimize traffic on the RIO-G interconnect structure. RIO-G provides a full duplex communication with 1 GB/sec in either direction. There is no such thing as arbitration. Figure 12-7 on page 262 shows that the two left-most I/O enclosures might communicate with server 0, each in full duplex. The two right-most I/O enclosures communicate with server 1, also in full duplex mode. This results in a potential of 8 GB/sec in total just for this single structure. Basically there is no affinity between HA and server. As we see later, the server which owns certain volumes through its DA, communicates with its respective HA when connecting to the host.

High performance, high availability interconnect to the disk subsystem

Figure 12-8depicts in some detail how the Fibre Channel switched back-end storage connects to the processor complex.

Server 0	L1,2
Memory	Memory	Processor
L3	L1,2
	Memory	Processor
Memory
POWER5 2-way SMP	RIO-G Module

RIO-G Interconnect

	L1,2	Server 1
Processor	Memory	Memory
	L1,2	L3
Processor	Memory
		Memory
RIO-G Module
		POWER5 2-way SMP

DA

RIO-G Module

RIO-G Module

DA

Note that DA and HA positions in I/O enclosures are shown to suit

the intention of the figure

20 port switch

o o o

16 DDM

20 port switch

20 port switch

o o o

16 DDM

20 port switch

Figure 12-8 Fibre Channel switched backend connect to processor complexes - partial view

All I/O enclosures within the RIO interconnect fabric are equally served from either processor complex.

Each I/O enclosure contains two DAs. Each DA with its four ports connects to four switches to reach out to two sets of 16 drives or disk drive modules (DDMs) each. Note that each 20-port

Chapter 12. Performance considerations 263