Scheduling - occurs during the planning process, and aids in identifying conflicts and impacts, and determines target dates for changes.

Distributing - this depends on the type of change, for example rolling out new levels of software across several systems.

Installing - the actual installation of changes. Installation should be able to be scheduled for a particular date and time of day.

Backout - reversing a change if it does not meet the installation or test criteria. The process to do this should be understood and planned for before the change is implemented.

Tracking - transmitting the state of the change to the change management system. This provides a common view to everyone involved in the process.

Post-installation analysis - reviewing completed changes to ensure they met the desired objectives, and to identify improvements that could be made to the change process.

30.2.3Methodology

Change management is effectively implemented in several simple steps. First, a log of system changes should be kept. The simplest method is simply recording the information in a data set or PDS member. This can be improved by using a table (as provided by TSO/ISPF) or database management system (such as DB2) where change information can be formatted into fields for easier querying, searching, and updating. Ultimately one should investigate a change management product, which will also add the ability to support the more formal process activities, such as assessment, planning, and tracking, in an efficient, automated fashion. IBMs TME 10 Information Management includes such functions, and allows change information to be updated and reviewed from a wide choices of platforms besides TSO - even via an automation product such as TME 10 NetView for OS/390.

One clear recommendation is that every system change, from system hardware to application software, be recorded and retained for a reasonable period of time

--at least a year. This will allow analysis of changes and discovery of any trends that are occurring (for example, are their certain changes that always lead to problems? If so, perhaps a better way to introduce those changes should be investigated). In addition, peer review of planned changes to the system should include review of the change control entries that document the change(s).

30.3Problem Management

30.3.1 Overview

The Problem Management discipline is very closely related to Change Management. When problems occur, either a change may be needed to fix the problem and keep it from re-occurring, or a change was what caused the problem in the first place. Managing problems is critical to achieve high levels of application availability (which depends upon system and component availability).

Problem resolution is often assisted because of the existence of change management and problem management databases, showing previous instances of the same or similar problems in one case, and changes that took place in the system just before the problem occurred.

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IBM OS/390 manual Methodology, Problem Management Overview

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.