25.2 Install and Configure Required Hardware

VSE and OS/390 operating systems both use the same basic S/390 hardware platform, although you will find that OS/390 may require more processor power, storage and DASD resources. On the other hand, OS/390 also provides more function, supports more devices, and is easier to manage as your applications and workload grow.

25.2.1 Processor Requirements

You will need a separate S/390 system such as a Multiprise 2000, or add another LPAR and supporting hardware to your existing processor. Customers with VM/ESA might want to add a virtual machine instead. If you add a migration and test load to your existing processor, you should add additional engines and memory to support the extra work.

Contact your IBM Representative to use one of the following capacity planning tools to size the processor requirements for your workload:

∙

∙

LPAR/CE

CP2000

Appendix B in OS/390 Planning for Installation describes the minimum processor requirements.

25.2.2 Devices Supported by OS/390

In general, all devices supported by VSE are supported by OS/390, except Fixed Block Architecture (FBA) DASD and most integrated communications adapters. See FBA to ECKD Migration Aid - Internal Disk for the Multiprise 2000 which is a S/390 White Paper in the SG242000 PACKAGE on MKTTOOLS. Contact your local IBM representative for a copy.

See Appendix B in OS/390 MVS Hardware Configuration Definition (HCD)

Planning, GC28-1750 for a complete list of supported devices.

25.2.3 DASD Requirements

Direct Access Storage Devices (DASD) are required for your OS/390 System Libraries, Page, Spool, Programs, Data, and Work/Public/Storage volumes. If you are configuring your own system, see Chapter 4 and Appendix E in OS/390 Planning for Installation for a thorough description and recommended pack layout. If you are using SystemPac or SIE to build your system, the volumes will be configured slightly differently for you.

While it is technically possible to create a one or two-pack OS/390 system, you will need a lot more DASD for productive use. The initial number of volumes required for system data sets with a SystemPac may be two RES, two DLIB, one SMP, and one CAT volume. Even though these contain paging and spool data sets, you will very quickly run out of space if you try to do any work.

Most installations require more spool space on OS/390 than they did with POWER because of the allocation units (track-groups) and space reclamation differences. (You will want to automate some method for purging old spool data sets.)

402VSE to OS/390 Migration Workbook

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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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