update and manage problem management records, but use of a searchable database technology, such as DB2 or a custom problem management package such as TME 10 Information Management will be very helpful.

30.4 Performance Management

30.4.1 Overview

Performance management addresses the effectiveness with which information system components work together in order to achieve the optimum throughput and responsiveness with a given hardware/software configuration.

All too often, systems are designed, implemented and tested without careful consideration of performance factors. Fixing performance problems after the fact is much more difficult and costly than considering these factors during the design. In critical applications which are forecast to be heavily used, modeling the performance characteristics before the design is finalized can be very profitable. It is necessary to record performance data on a regular basis. The OS/390 system provides Resource Measurement Facility (RMF) which will record system resource (CPU, DASD or tape I/O, and so on) utilization for every job and job step in your system, or for any defined subset of it. In addition to the RMF data, it is valuable to have references to business volumes (orders, total number of order line items, number of paychecks processed) which can serve as an independent variable for estimating future requirements.

Performance management includes both real-time performance monitoring and long term capacity planning and reporting. Capacity planning relies on data from real-time performance monitoring, and uses it to determine trends that will influence future resource and application performance planning. Specifically, the long term growth in system resource consumption for various classes of system resources is monitored and future requirements are projected and used to identify usability end-points for system components. CPU, DASD, tape, printer, and similar subsystems can be studied and system capacity needs can be managed on a scientific and business management basis.

Reporting also includes comparing performance and availability achieved against agreed to service levels. Working with the problem management process can identify the reasons reported attainment did not meet service levels.

30.4.2 Tasks

The performance management process includes:

∙Capacity planning

ÞDefining and managing the availability of system resources required to meet anticipated service demand.

ÞModelling systems to determine and validate their ability to provide needed service.

ÞValidating user requirements against trends in current service levels.

ÞCollecting workload requirements and merging them into service requirements for all resources, such as hosts, network, servers.

∙Performance policy definition

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IBM OS/390 manual Performance Management Overview
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OS/390 specifications

IBM OS/390, a versatile operating system, was a cornerstone in enterprise environments and played a pivotal role in mainframe computing. Released in the mid-1990s, OS/390 combined the strengths of IBM's MVS (Multiple Virtual Storage) with new features and enhancements, targeting scalability, reliability, and performance in demanding business applications.

One of the key features of OS/390 was its robust support for multiple users and processes. The system allowed thousands of concurrent users to access applications and data, ensuring high availability and minimizing downtime—a critical requirement for many large organizations. This scalability was supported through various enhancements in memory management and processor scheduling, enabling optimal resource allocation across diverse workloads.

OS/390 was known for its superior workload management capabilities. The Workload Manager (WLM) component allowed administrators to define service policies, specifying how system resources would be allocated according to the priority of tasks. This ensured that critical business processes received the necessary resources while less critical tasks were managed more flexibly.

Another significant characteristic of OS/390 was its commitment to security. The operating system provided comprehensive security features, including user authentication, data encryption, and auditing capabilities. This focus on security was vital for organizations handling sensitive data, ensuring compliance with regulations and safeguarding against unauthorized access.

OS/390 also supported advanced technologies that facilitated integration and development. The system included features like the IBM CICS (Customer Information Control System) for transaction processing and IMS (Information Management System) for database management. These technologies allowed organizations to build robust, high-performance applications tailored to specific business needs.

The ease of network integration was another strength of OS/390. With the advent of the Internet and global connectivity, OS/390 systems could easily interface with various network protocols, enabling businesses to operate in a connected world. This inclusion paved the way for many organizations to expand their capabilities and offer new services, driving digital transformation.

In conclusion, IBM OS/390 represented a significant advancement in mainframe technology, combining scalability, security, and robust workload management. Its rich feature set and support for critical enterprise applications solidified its role as a vital component of many organizations' IT infrastructures, ensuring they could meet their operational challenges head-on while supporting future growth. As technology continues to evolve, the legacy of OS/390 remains influential in the realm of computing.
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