FBA Dasd, Catalog Structures, Noimbed Option

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VSE/VSAM-managed SAM files

−Default models

−NOALLOCATION data sets

−Implicit JCL DEFINE

Reusable data sets

Partition independent file names

VSE/VSAM BACKUP/RESTORE and VSE FASTCOPY

IKQVDU - volume cleanup

IKQVCHK - catalog check

Space classes

VSAM SHAREOPTIONS (SHR(4) and SHR(4 4) differences)

5.6.5.2 FBA DASD

Fixed Block Architecture (FBA) DASD devices such as the 3370, 3310, 9332, 9335, 9336, and FBA virtual disks are not supported by OS/390. Any data sets on these devices must be moved to an OS/390 supported Count Key Data (CKD) or Extended CKD (ECKD) DASD device such as the 3390, 3380, 3350, or 3375. This is generally done by copying the data sets to tape and loading them down with appropriate OS/390 utilities. For VSAM data sets, AMS REPRO is recommended.

5.6.5.3 Catalog Structures

NOIMBED Option

VSE/VSAM catalogs may be defined with the NOIMBED option. This saves DASD space by not replicating the sequence set in the data portions of the catalog. It may make a catalog search take longer an a CKD device. These catalogs cannot be accessed by OS/390 VSAM.

The procedures for converting these back to IMBED format are described in the VSE/VSAM Programmer′s Reference, SC24-5145. Briefly, EXPORT all files, delete all VSAM space, delete the catalog, redefine the catalog with the IMBED option, re-define the VSAM space, and IMPORT the files. If VSE/VSAM BACKUP is used instead of EXPORT, then RESTORE is used instead of IMPORT. BACKUP and RESTORE should be both easier to use and faster than EXPORT and IMPORT.

The above paragraphs are talking about a VSAM catalog being accessed by both VSE and OS/390 but when the catalog is converted, NOIMBED and NOREPLICATE are recommended when behind cache. IMBED is not recommended for VSAM data sets or ICF catalogs when these data sets are stored on DASD volumes behind a cached control unit because IMBED implies replication and replicated data can result in poor cache usage. If sufficient real and virtual storage is available, and appropriate BUFNI values are specified to keep the index components for VSAM clusters in storage, NOIMBED and NOREPLICATE is also indicated, even with non-cached DASD hardware.

Shared Volume Ownership

VSE or OS/390 VSAM catalogs may own space on more than one DASD volume. Only one VSAM catalog may reside on a volume. Both VSE and OS/390 VSAM

120VSE to OS/390 Migration Workbook

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.

IBM OS/390 manual FBA Dasd, Catalog Structures, Noimbed Option, Shared Volume Ownership

Models: OS/390