ÞEstablishing performance specifications and policies.

Performance execution and measurement

ÞResponse time monitoring - what is the response time as seen by the user?

ÞAvailability monitoring - whats broken?

ÞUtilization monitoring - who are the biggest users? What is the service times and queue lengths for key components and resources?

ÞComponent delay monitoring - what are the bottlenecks?

ÞPerformance tuning - how can the resources be used effectively?

ÞTracking and control - what are the short term trends? alerts? long term trends? how can I tailor the volumes and data flow to the needs and resources of the system?

30.4.3Methodology

Performance information must be available to view in real-time to get a snapshot of system status, and to quickly address any problem or potential problem situations. It must also be archived so that long term analysis can be carried out. It is best to save this information to DASD or tape - printing and saving stacks of performance information is a waste of time. It takes up too much space, you will never find the information you need in a timely manner, and the information you probably need at a given point of time will likely be in a report that has just been discarded.

OS/390s RMF subsystem will record system resource utilization information. OS/390 SMF (Systems Management Facility) records contain RMF data and data from other sources (JES, VTAM, NetView, NetView Performance Monitor) that contains performance information. Many IBM and non-IBM performance products that monitor specific resources can place their data into SMF records.

While users, I/O control clerks, operators or specialized jobs can capture the business volume information, the use of performance and automation products can help make this task less labor intensive. Understanding the relationship between user transactions or batch jobs and business units of work will allow business volumes to be directly derived from performance monitors, and automation can be used to collect and format the data as needed.

Tracking performance data must also include online transaction response time, DASD I/O service times, batch program elapsed times, and batch window start and completion times. NetView Performance Monitor can measure and report online transaction response time. RMF and SMF can provide data on DASD I/O and batch performance. TME 10 Operations Planning and Control (TME 10 OPC) schedules batch workloads and can provide data on batch program and batch window elapsed times.

Using a PC and a spreadsheet application to download and capture and report in tables and graphs the critical performance variables over time is a very practical way to start; junior systems programming personnel, senior operations personnel, or help desk personnel can keep this information. A more robust solution will be a performance reporting product such as IBMs TME 10 Performance Reporter; it can directly read many of the sources that contain performance data, such as SMF, and produce short term and long term analysis reports for use in capacity planning.

464VSE to OS/390 Migration Workbook

Page 488
Image 488
IBM OS/390 manual Methodology

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.