IBM eServer zSeries 990 Technical Guide

156 IBM ^ zSeries 990 Technical Guide

7.1 Parallel Sysplex

Figure 7-1 illustrates the components of a Parallel Sysplex as implemented within the zSeries

architecture. Shown is a z900 model 2xx ICF (CF01) connected to two z990 servers running

in Sysplex. There is a second Integrated Coupling Facility (CF02) defined within one of the

z990s, containing SysPlex logical partitions running z/OS.

Figure 7-1 Sysplex hardware overview

Also shown is the required connection between the Coupling Facility (CF01) defined on a

z900 turbo model (2064-2xx) or any z990 Server, and the Sysplex Timer, to support Message

Time Ordering.

7.1.1 Parallel Sysplex described

Parallel Sysplex technology is an enabling technology, allowing highly reliable, redundant, and

robust zSeries technologies to achieve near-continuous availability. A Parallel Sysplex is

comprised of one or more z/OS and/or OS/390 operating system images coupled via one or

more Coupling Facilities. The images can be combined together to form clusters. A properly

configured Parallel Sysplex cluster is designed to maximize availability. For example:

򐂰 Hardware and software components provide for concurrent planned maintenance, like

adding additional capacity to a cluster via additional images, without disruption to

customer workloads.

򐂰 Networking technologies that deliver functions like VTAM Generic Resources, Multi-Node

Persistent Sessions, Virtual IP Addressing, and Sysplex Distributor to provide

fault-tolerant network connections.

DASD DASD DASD

CF02

ICF

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ICF

ESCON / FICON

Sysplex Timer

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ICB-4

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IBM z900

Model 2xx

IBM z990

Sysplex

LPARs

Sysplex

LPARs

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connection from

CF on z900 2xx

or any z990 CPC

to Sysplex Timer

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Chapter 7. Sysplex functions 157

򐂰 z/OS and OS/390 software components allow new software releases to coexist with lower

levels of that software component to facilitate rolling maintenance.

򐂰 Business applications are “data sharing enabled” and cloned across images to allow

workload balancing and to prevent loss of application availability in the event of an outage.

򐂰 Many operational and recovery processes can be automated, reducing the need for

human intervention.

Parallel Sysplex is a way of managing a multi-system environment, providing the benefits of:

򐂰 Continuous (application) availability

򐂰 High capacity

򐂰 Dynamic workload balancing

򐂰 Simplified systems management

򐂰 Resource sharing

򐂰 Single system image

Continuous (application) availability

Within a Parallel Sysplex cluster, it is possible to construct a parallel processing environment

with high availability. This environment is composed of multiple images that provide

concurrent access to all critical applications and data.

You can introduce changes (such as software upgrades) one image at a time, while remaining

images continue to process work. This allows you to roll changes through your images at a

pace that makes sense for your business.

High capacity

The Parallel Sysplex environment can scale, in a nearly linear fashion, from two to 32 images.

This can be a mix of any server or operating system that supports the Parallel Sysplex

environment. The aggregated capacity of this configuration meets every processing

requirement known today.

Dynamic workload balancing

The entire Parallel Sysplex cluster can be viewed as a single logical resource to end users

and business applications. Work can be directed to any like operating system image in a

Parallel Sysplex cluster having available capacity. This avoids the need to partition data or

applications among individual images in the cluster or to replicate databases across multiple

servers.

Workload management permits you to run diverse applications across a Parallel Sysplex

cluster while maintaining the response levels critical to your business. You select the service

level agreements required for each workload, and the z/OS or OS/390 Workload Manager

(WLM), along with the subsystems such as CP/SM or WebSphere, automatically balances

tasks across all the resources of the Parallel Sysplex cluster to meet your business goals.

Whether the work is coming from batch, SNA, TCP/IP, DRDA®, or MQSeries®

(non-persistent) messages, dynamic session balancing gets the business requests into the

system best able to process the transaction. This provides the performance and flexibility you

need to achieve the responsiveness your customers demand, and it is invisible to users.