Chapter 20 Parallel Sysplex

In this chapter you will learn: Objectives In this chapter you will learn: How Parallel Sysplex can achieve continuous availability Dynamic workload balancing Single system image

Sysplex Hardware Overview

Sysplex Overview A sysplex is a collection of z/OS systems that cooperate, using certain hardware and software products, to process work Improved growth potential Improved level of availability

What is a parallel sysplex? Innovative multi-system data-sharing technology Direct concurrent read/write access to shared data from all processing nodes No loss of data integrity No performance hit Transactions and queries can be distributed for parallel execution based on available capacity and not restricted to a single node

What is parallel sysplex? (continued) Builds on the strength of zSeries servers by linking up to 32 images to create the industry’s most powerful commercial processing clustered system Every “cloned” application can run on every image Hardware and software can be maintained non-disruptively

Continuous availability Within a parallel sysplex cluster, it is possible to construct an environment with no single point of failure Peer instances can of a failing subsystem can take over recovery responsibility for resources held by the failing instance Alternatively the failing subsystem can be automatically restarted on still healthy systems

Continuous availability In a parallel sysplex it is possible that the loss of a server may be transparent to the application and the server workload redistributed automatically with little performance degradation Each system is still individual Software upgrades can be rolled through one system at a time on a sensible timescale for the business

Capacity The parallel sysplex can scale near linearly from 2 to 32 systems. It can be a mix of any servers that support parallel sysplex

Dynamic workload balancing The entire parallel sysplex cluster can be regarded as a single logical resource to end users and business applications Work can be dynamically distributed to nodes with available capacity Workload balancing also allows running of diverse applications while maintaining response times critical to the business

Sysplex Failure Manager Automatic Restart Manager Ease of use z/OS Workload Manager Sysplex-wide workload management to one policy Sysplex Failure Manager Specify failure detection and recovery actions Automatic Restart Manager Fast recovery of critical subsystems Cloning and symbolics Used to replicate applications across the nodes

zSeries Parallel Sysplex Resource Sharing This is not to be confused with application data sharing This is sharing of physical system resources such as tape drives, catalogs, consoles This exploitation is built into z/OS Simplifies the management of the system

Single System Image The sysplex should appear as a single image to operator, end user, database administrator and others Single point of control Persistent single image across failures

Applications in a Parallel Sysplex Design goal of no application changes Benefits Scalability Integration of older applications with new workloads such as web serving With an existing sysplex there is very little infrastructure work required for a new application. The existing infrastructure may even be used without the need for a new server

GDPS A geographically dispersed parallel sysplex is the ultimate disaster recovery and continuous availability solution for a multi-site enterprise Two sites up to 100 fiber kilometers apart may be connected for synchronous updates Asynchronous techniques may be used over this distance

Summary Reduce cost compared to previous offerings of comparable function and performance Continuous availability even during change Dynamic addition and change Parallel sysplex builds on the strengths of the z/OS platform to bring even greater availability serviceability and reliability

Additional materials The following foils contain additional material to demonstrate points about parallel sysplex if one is not available

Parallel sysplex display status Display of a 16 image sysplex Each image has reported active with the last 5 seconds

D IPLINFO This shows the first screen of response to D IPLINFO in a sysplex Note that systems have been IPL’d at different times and are running different releases of z/OS

D WLM This shows the display for two of the systems in the sysplex Note they are running the same policy activated at exactly the same time by another system SC53

D XCF,PATHIN This display shows the connections to the other systems in the sysplex are by both CTC devices and via structures in the coupling facility If the CF were to have a problem then the sysplex would continue with the CTC connections

D XCF,STRUCTURE This shows a subset of the output from the command to illustrate some points The IXC structures are the ones used by XCF, the main sysplex component The SYSZWLM structures are used by workload manager Note there is one structure for each physical machine There are two machines: a 2064 (z900) and a 2084 (z990)

D M=CPU This shows the output from the command with the processor type, serial number and number of logical processors assigned

D C This shows the console display for a system SC04 in a sysplex Note that the only console is attached to SC47