The first trial conversion starts with a complete fresh supply of the VSE conversion inventory. Every three to four weeks, the mass conversion starts from a fresh copy of the entire conversion inventory, in order to take into account the last VSE maintenance modifications. Between two supplies, additional mass conversions may be executed from the same supply, in whole or in part, in order to take advantage of the latest custom modification improvements.

The first trial conversion is complete when all OS/390 programs, load modules, and JCL are available for OS/390 tests.

32.5.4 Phase 5: OS/390 Regression Tests and Repeated Trial Conversions

The goal of these tasks is executing the converted jobs in MVS to verify that they function as they did in VSE, and to correct software conversion errors or file migration errors that generate test exceptions. Also during this phase full size copies of the VSE production will be migrated to MVS, and in the process will test the file migration procedure that will be used later on for switchover rehearsal and actual switchover.

Objectives of testing

1.To develop a broad base of knowledge as soon as possible.

A major resulting benefit of the testing phase is the experience and training that is gained in the OS/390 environment. This is an excellent source of hands on training in a soon to be real life environment. The testing environment needs to include the use of the job scheduler, SMS, tape manager and Report Manager.

Problems need to be identified as early as possible in order to provide the proper lead time for their resolution. The by-products of thorough testing are education, training, confidence, and success.

2.To make the applications fail.

Testing is the process of working through execution time errors using the applications, jobs and data you have converted and moved into the new environment. Thorough testing and the elimination of problems are crucial to a successful conversion.

Failure is good in the test environment; failure is not good in the production environment. Therefore, the better the design and execution of the test cases, the less chance for production failures.

Phases of testing

There are typically three phases of testing associated with the test cycle for applications. They are:

∙

∙

∙

Unit Testing

System Testing

Parallel/Simulated Production Testing

OS/390 online application tests include:

∙Initialization tests which start each transaction to verify that the initial screen comes up

∙

∙

Unit (or technical) tests are tests on a representative sample of transactions

System (or Functional) tests are scenarios of chained transactions corresponding to application flows

506VSE to OS/390 Migration Workbook

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IBM OS/390 manual Objectives of testing, Phases of 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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