Inter-Systems Connectivity, Shared Dasd, Tape Drives

OS/390 through cross-domain resource definitions. They are also useful for data transfer via NetView FTP or NJE. OSA (Open System Adapters) are often the most economical solution.

You will want access to other devices in your installation. They can be switchable or connected via a common local area network (LAN). See the OS/390 MVS Recovery and Reconfiguration Guide, GC28-1777 for more configuration planning information.

25.2.5 Inter-Systems Connectivity

You will need to share files and I/O devices between your VSE system and the new OS/390 system. Users on the new OS/390 system need access to data and resources such as printers and interactive terminals on your existing VSE system, and VSE users need to send programs and data over to the new system for migration and testing.

25.2.5.1 Shared DASD

It is both difficult and dangerous to share DASD between VSE and OS/390 systems. Difficult because they don′t support the same file organizations. Dangerous because there is no serialization mechanism to prevent multiple updates or data corruption from occurring.

However, under strict manual controls (for example, vary online/offline) you can set up some common DASD for sharing data and programs between your VSE and OS/390 systems. This way, you can avoid an intermediate transfer of the data to tape or sending it via communication mechanisms such as NetView FTP.

Since VSE doesn′t support indexed VTOCs, a volume with an indexed VTOC must be converted to a non-indexed VTOC (OS VTOC) before transporting it to the VSE system. Chapter 5, ªDisk and Tape Storage Considerationsº on page 97 chapter has more information about DASD sharing.

25.2.5.2 Tape Drives

You will need some tape drives to transfer large amounts of data between the two systems. They can be switched between the two systems, although you probably will want to dedicate at least two tape drives to the OS/390 system.

25.2.5.3 Terminal Access

You will need to provide terminal access for TSO users on your new system.

This can be done in several different ways:

∙

Dedicate terminal controller to the OS/390 system.

SNA cross-domain logon from your existing terminals on your VSE system using VTAM-controlled CTCs

∙SNA cross-domain logon through a Communications Controllers (for example, 3745) shared with your VSE system using multiple channel adapters or EMIF.

∙Use a Token-Ring network shared with the VSE system, and an OSA (Open System Adapter) on the new processor.

See 25.5.1.3, ªProviding Terminal Access to the OS/390 Systemº on page 414.

404VSE to OS/390 Migration Workbook

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.

IBM OS/390 manual Inter-Systems Connectivity, Shared Dasd, Tape Drives, Terminal Access

Models: OS/390