IBM eServer zSeries 900 Technical Guide

Chapter 1. zSeries 900 overview 11

1.3.5 Parallel Sysplex support

InterSystem Coupling channels

A 4-port ISC-3 card structure is provided on the z900 family of processors. It consists of a

mother card with two daughter cards that have two ports each. Each daughter card is capable

of operating at 1 Gbps in compatibility (sender/receiver) mode or 2 Gbps in peer mode up to

10 km. The mode is selected for each port via CHPID type in the IOCDS.

InterSystem Coupling (ISC-3) channels provide the connectivity required for data sharing

between the coupling facility and the CPCs directly attached to it. ISC-3 channels are

point-to-point connections that require a unique channel definition at each end of the channel.

ISC-3 channels operating in peer mode provide connection between z900 models. ISC-3

channels operating in compatibility mode provide connection between z900 models and ISC

channels on 9672 models.

Integrated Cluster Bus-3

The Integrated Cluster Bus-3 (ICB-3) uses an STI link to perform z900 coupling

communication otherwise performed by ISC links. The connectors are located on the

processor board. The cost of coupling is reduced by using a higher performing but less

complex transport link suitable for the relatively short distances (up to 10 meters) used by

most z900 coupling configurations. ICB-3 is the native connection between z900 servers and

operates at 1 GB/sec. The maximum number of ICB-3s is limited to 16.

Integrated Cluster Bus

The Integrated Cluster Bus (ICB) uses a secondary STI from an STI-H card to perform S/390

coupling communication otherwise performed by ISC links.This compatibility mode ICB

feature is used to attach a 9672 G5/G6 server to a z900 server via an ICB and operates at

333 MB/s. Up to 8 ICBs (16 via an RPQ) are available on the general purpose models and up

to 16 on the z900-100 Coupling Facility model.

Internal Coupling-3

The Internal Coupling-3 (IC-3) channel emulates the peer mode coupling link functions in LIC

between images within a single system. No hardware is required; however, a minimum of two

CHPID numbers must be defined in the IOCDS.

System-managed CF structure duplexing

System-managed Coupling Facility (CF) structure duplexing provides a general purpose,

hardware-assisted, easy-to-exploit mechanism for duplexing CF structure data. This provides

a robust recovery mechanism for failure such as loss of a single structure or CF, or loss of

connectivity to a single CF, through rapid failover to the other structure instance of the duplex

pair.

64-bit Coupling Facility Control Code

The Coupling Facility Control Code (CFCC), CFLEVEL 12 and above, uses 64-bit addressing

for all structure types. This allows addressing capability to structures having more than 2 GB.

1.3.6 Intelligent Resource Director

Exclusive to IBM's z/Architecture is Intelligent Resource Director (IRD), a function that

optimizes processor and channel resource utilization across Logical Partitions (LPARs) based

on workload priorities. IRD combines the strengths of the z900 Processor Resource/Systems

Manager (PR/SM) logical partitioning, Parallel Sysplex clustering, z/OS Workload Manager

and Channel Subsystem (CSS).