Chapter 1. IBM zSeries 990 overview 15
Draft Document for Review April 7, 2004 6:15 pm 6947ch01.fm
For those CF structures that support use of System-Managed CF Structure Duplexing,
customers have the ability to dynamically enable or disable, selectively by structure, the use
of System-Managed CF Structure Duplexing.
Customers interested in deploying System-Managed CF Structure Duplexing in their test,
development, or production Parallel Sysplex will need to read the technical paper
System-Managed CF Structure Duplexing, GM13-0103 and analyze their Parallel Sysplex
environment to understand the performance and other considerations of using this function.
GM13-0103 is available at these Web sites:
http://www.ibm.com/server/eserver/zSeries/pso
http://www.ibm.com/servers/eserver/zSeries/library/techpapers/gm130103.html
1.3.10 Intelligent Resource Director (IRD)
Exclusive to IBM's z/Architecture is Intelligent Resource Director (IRD), a function that
optimizes processor and channel resource utilization across logical partitions based on
workload priorities. IRD combines the strengths of the PR/SM, Parallel Sysplex clustering,
and z/OS Workload Manager.
Intelligent Resource Director uses the concept of an “LPAR cluster”, the subset of z/OS
systems in a Parallel Sysplex cluster that are running as logical partitions on the same z900
server. In a Parallel Sysplex environment, Workload Manager directs work to the appropriate
resources, based on business policy. With IRD, resources are directed to the priority work.
Together, Parallel Sysplex technology and IRD provide flexibility and responsiveness to
e-business workloads that are unrivaled in the industry.
IRD has three major functions: LPAR CPU Management, Dynamic Channel Path
Management, and Channel Subsystem Priority Queuing, which are explained in the following
sections.

Channel Subsystem Priority Queuing

Channel Subsystem Priority Queuing on the z900 allows priority queueing of I/O requests
within the Channel Subsystem, and the specification of relative priority among logical
partitions. WLM in goal mode sets priorities for a logical partition, and coordinates this activity
among clustered logical partitions.

Dynamic Channel Path Management

This feature enables customers to have channel paths that dynamically and automatically
move to those ESCON I/O devices that have a need for additional bandwidth due to high I/O
activity. The benefits are enhanced by the use of goal mode and clustered logical partitions.

LPAR CPU Management

Workload Manager (WLM) dynamically adjusts the number of logical processors within a
logical partition and the processor weight, based on the WLM policy. The ability to move the
CPU weights across an LPAR cluster provides processing power to where it is most needed,
based on WLM goal mode policy.
1.3.11 Hardware consoles

Hardware Management Console and Support Element interface

On z990 servers, the Hardware Management Console (HMC) provides the platform and user
interface that can control and monitor the status of the system via the two redundant Support
Elements installed in each z990.