26.5.1 OS/390 Maintenance Environment

Early in the project a test SMP/E environment needs to be designed and built. This process involves ²cloning² the OS/390 system libraries to provide a new target to apply OS/390 maintenance without compromising the OS/390 production environment. Since OS/390 was installed at the beginning of the project, the maintenance level could be well over a year old by switch-over time. It is highly recommended that a maintenance cycle be performed before switch-over. (Testing timeliness, and so on will dictate the best time for this.) The maintenance environment can be designed simply to provide for alternate resident volumes and be IPLed and tested in the production environment or preferably built in a test logical partition (LP) or virtual machine. (This will most likely be the implementation after switch-over.)

Once application testing starts on the OS/390 system, it becomes a ªproductionº system to many. Any disruption to their testing environment will impact their conversion efforts.

There are many variations and considerations of maintenance environments and most are okay as long as the availability requirements are understood and met. The important criteria is that the test system provides for a simple process to apply maintenance in an emergency situation and during regular preventative maintenance cycles without causing a system outage. The Redbook OS/390 Software Management Cookbook SG24-4775, although somewhat out-dated, provides some excellent discussion on this topic.

26.5.2 OS/390 Test Logical Partition

There are many things to consider when building a test logical partition (LP) for the maintenance environment. For example, will you be sharing DASD, catalogs, system parameters, subsystems and so on, or will this be completely isolated and serve as a rescue system? Many things such as communications between the two environments will have already been addressed by the work done connecting VSE to OS/390. The more subsystems available to test in the test LP, the less likely of a system outage when IPLing the new maintenance into production. Or, put another way, the closer your test system is to your production environment and workload, the less likely you will be surprised by problems in production.

26.5.3 Maintaining Your OS/390 Libraries and SMP/E Zones

You must keep your OS/390 target libraries and SMP/E target zones synchronized to preserve the integrity of your system. When the target libraries are backed up, the associated target zones must be backed up as well. You should create a procedure where the first step backs up the volumes, and the second step backs up the SMP/E target zone.

The reverse is true for restore. Whenever you restore your target libraries, you should simultaneously restore your SMP/E target zone.

Chapter 26. Test Environments 431

Page 454 Page 456
Page 455
Image 455
IBM manual 26.5.1 OS/390 Maintenance Environment, 26.5.2 OS/390 Test Logical Partition
Page 454 Page 456

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.
Top Page Image Contents