A beginning rule of thumb shows 12 volumes of 3390-3 (or equivalent) DASD,

allocated as follows: (Your mileage will vary!)

Table 45. OS/390 DASD Layout

Volume Use

Number

 

 

 

System Libraries (RES)

2

 

 

 

 

Distribution Libraries (DLIB)

2

 

 

 

 

SMP/E Work (SMP)

1

 

 

 

 

Catalogs (CAT)

1

 

 

 

 

Paging Data Sets (PAG)

1

 

 

 

 

Spool & Checkpoint (SPL)

1

 

 

 

 

Softcopy Library (BKM)

1

 

 

 

 

DFSMShsm ML1

1

 

 

 

 

Storage/Work/DFSMS Volumes

1

or more

 

 

 

User Program/Data Libraries

1

or more

 

 

 

ISV Products

0

or more

 

 

TOTALS

12 or more

 

 

 

These numbers are very dependent on the installation, and will increase dramatically at the end of a ²mass migration² in order to duplicate user data files.

25.2.4 Other Hardware Requirements

For the most minimal testing, you will need at least the following devices, depending on the number of users, and the size of your applications and databases.

Tapes Tape drives will be required for system dumps, backups and restores, application testing, and DFSMShsm ML2 migrations. These can be switched between the production VSE system and the OS/390 system, but you should plan on at least two dedicated tape drives for the OS/390 system.

Console You should have at least one console connected through non-SNA control units for system operation and a second console for backup and operator training.

Printers You will occasionally need to print. Printers can either be dedicated to the OS/390 system, switchable from the VSE system, shared on a LAN, or accessed on the VSE system via NJE. RJE printers are also an option if you already plan to have remote workstation printers.

Remote Workstations

If you are migrating remote workstations to JES2 RJE, it may be very helpful to have additional workstations dedicated for testing.

Communication Controllers

You need to provide for remote access of TSO, RJE, NJE and application (for example, CICS) users. With multiple channel adapters, you can also allow terminals connected to your VSE system to access

Chapter 25. Prepare the Migration Environment

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IBM OS/390 manual Other Hardware Requirements, 403

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.