functional components as well as RACF and DFSORT. For details, see section 1.3 in the DFSMS/MVS General Information, GC26-4900.

∙DFSMSdfp is an OS/390 base element and functional component of DFSMS/MVS. It provides the storage, program, data, and device management functions of MVS. DFSMSdfp provides the foundation for distributed data access, using the Distributed File Manager to support remote access of MVS data and storage resources from workstations, personal computers, or other authorized systems in an SNA LU 6.2 network.

DFSMSdfp also provides the Storage Management Subsystem component. DFSMSdfp is the DFSMS component that provides OS/390′s VSAM functions.

∙DFSMSdss is an OS/390 optional feature and functional component of DFSMS/MVS. It is used for data movement and replication, space management (defragmentation), data backup and recovery, and data set and volume conversion to system managed storage.

∙DFSMShsm is an OS/390 optional feature and functional component of DFSMS/MVS. It provides the functions for:

−Storage management using a hierarchy of storage devices in its automatic management of data, relieving end-users from manual storage tasks.

−Space management by keeping only active data on fast-access storage devices. It automatically frees space on user volumes by deleting eligible data sets, releasing over-allocated space, and moving low-activity data to lower-cost-per-byte devices.

−Tape mount management by writing multiple output data sets to a single tape, making it a useful tool for implementing tape mount management (TMM) under SMS. For more information on TMM, refer to Implementing System-Managed Storage, SC26-3123.

−Availability management by backing up your data, either automatically or by command, to ensure availability in the event of accidental loss of data sets or physical loss of volumes. Disaster backup and recovery is also provided for user-defined groups of data sets (aggregates), so that critical applications can be restored at the same location or at an off-site location. This capability is referred to as ABARS.

∙DFSMSrmm is an OS/390 optional feature and functional component of DFSMS/MVS. It provides the management functions for removable media, including tape cartridges and reels. DFSMSrmm can be used to manage system-managed tape libraries such as the 3494 or 3495 Automated Tape Library Dataservers or the manual 3495 Tape Library Dataserver Model M10. DFSMSrmm can also manage non-system-managed tape libraries.

∙DFSORT is an OS/390 optional feature. It sorts, merges and copies data sets, and also helps you to analyze data and produce detailed reports using the ICETOOL utility or the OUTFIL function.

∙RACF is an OS/390 optional feature. It controls access to data and other resources in MVS.

Chapter 5. Disk and Tape Storage Considerations 101

Page 124 Page 126
Page 125
Image 125
IBM OS/390 manual Disk and Tape Storage Considerations
Page 124 Page 126

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