Chapter 34. Customer Migration Example

This chapter describes an actual user experience with migration. Since every customer environment is unique, care should be taken when drawing comparisons, especially in areas of resource and capacity.

34.1 Background

Cust1 is a relatively fast growing company that evolved from a small 4341 to a

3-way 9672 in a little more than a decade. The I/S organization was constantly challenged to support new business with very little lead time. Their VSE operating system was always being pushed to its limits supporting the growing workload. The computer operations had grown to a near 21 shift operation (only a two to four hour window early Sunday morning for maintenance). For five or six years before the final decision to migrate to MVS, serious consideration was given to an MVS migration because of the constraints of the VSE architecture on their business, but new enhancements to VSE relieved the urgency. All of the measures to improve VSE performance were taken, for example, multiple VSE guests for parallelism, faster engines, faster DASD, VSE ESA features and so on. Each time a new piece of business was taken on, the I/S organization was concerned if they would be able to contain the workload, and usually suffered a lot of pain balancing resources. Finally it was decided that the move to MVS would be the only recourse to support the future business growth.

34.2Environment

34.2.1.1Hardware

Bipolar air cooled 3-way processor

The customer changed to a 9672 3-way in the middle of the project. This change was made primarily because of an IBM marketing package that actually provided more resource for a lower lease cost. This occurred at a time in the project when the extra capacity (mostly central storage) was very welcome (systems tests).

￿256MB storage

￿1GB on the 9672

RAMAC DASD

￿Two racks of RAMAC I each 2/3 full (3380)

￿One rack of RAMAC II 1/3 full (3390)

￿All racks filled by switchover for testing bubble

34.2.1.2 Software

VM/ESA

VSE/ESA (three guests)

The VSE level with turbo was installed before the project, but the turbo dispatcher was not enabled because of poor performance and availability issues.

© Copyright IBM Corp. 1998

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IBM OS/390 manual Customer Migration Example, Background, Environment, Hardware, Software

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.