Job Simulation

The goal is to get through as many days as possible. It is a comfort to know at switchover, that a week¢s jobs can be processed. There are significantly fewer monthly jobs than weekly jobs. There are significantly fewer yearly jobs than monthly jobs. Plan the cutover to not occur at month end.

The final phase of parallel testing is ensuring the output is the same from both systems, where actual production is compared to the test output.

Date Concerns during Parallel Testing

Date concerns at this stage should not be as large a concern because of synchronizing data for particular day. Be certain that if the output reports run clean it is not due to them being empty as a result of not finding any date specific data. Also results can be a bit unpredictable when jobs are run with dates that are unexpected. Be aware of the age of the dates. If necessary the dates can be set externally through the JCL.

32.6 Implementation Phases

The implementation phases are typically the two weeks that precede the actual switchover. Once testing indicates that the conversion process is working, your installation is ready for switchover. After the final mass conversion, switchover typically requires only a single weekend. The switchover process consists of backing up the current VSE environment, switching files to OS/390, priming the MVS catalogs, and initial MVS production operations. This is the period when the VSE system is frozen. You do not want to be making changes to the VSE system during these two weeks.

The project phases during the Implementation Phases are:

∙

∙

Actual Conversion and Switchover Initial OS/390 Operations

The final and actual mass conversion will be started after MVS tests have been successfully completed. It will deliver the actual MVS production material. The actual JCL conversion may be scheduled one or two weeks before the actual program conversion, in order to apply final manual JCL modifications. There will also be a special one-time translation of all applications¢ development source code, but without any compilation or JCL generation.

These phases include the following key tasks:

∙

∙

∙

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Mass Conversion of Development Source Code

Final JCL Mass Conversion

Final Program Mass Conversion

Initial OS/390 Operations

References for additional conversion information can be found in:

∙Appendix B of the MVS-MS Planning Guide named ²Sample Switchover Plan².

Chapter 32. Conversion Process 515

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IBM OS/390 manual Implementation Phases, Job Simulation, Date Concerns during Parallel Testing
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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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