Intelligent VSAM (and IAM) Re-Organization and PDS Compression
FDRREORG offers a fast, flexible and intelligent solution for reorganizing VSAM KSDS, Alternate Index (AIX) files, and for compressing PDS data sets. Users of the Innovation Access Method (IAM) can also use FDRREORG to reorganize their IAM files.
Typical savings with FDRREORG
FDRREORG also eliminates much of the manual “hit-and-miss” approach inherent in IDCAMS and IEBCOPY.
User-specified selection criteria ensure that only the files that need reorganization or compression are selected, further reducing the utilization of valuable CPU resources, yet still ensuring that the files that really need attention do not get overlooked.
Re-Organizing VSAM and Compressing PDSs on an “as needed” basis can greatly reduce the time it takes to complete the overall tasks, and, therefore, reduces the level of interruption to the applications that use those files.
Re-Organizing VSAM Files with FDRREORG
Many applications running under z/OS still use VSAM as the underlining file structure. Some VSAM files can be very heavily used and can become extremely large. As usage and/or size of a VSAM file increases, the performance of the application(s) using that file can be significantly impaired.
An IDCAMS re-organization of the VSAM file can improve the performance, but the ageing utility is notoriously slow and lacks the automation features required by today’s large z/OS shops.
Automation, Intelligence and Centralized Control
When traditional methods of VSAM reorganization are used (e.g. IDCAMS), the process is usually scheduled as a regular job, and the selection of files to be processed is based upon some previous experience.
Using this approach, reorganizations are often carried out on files were there is only a marginal benefit. And in other cases, files that need a reorganization get overlooked.
FDRREORG’s intelligent selection criteria helps to eliminate these problems. A single job can be scheduled to run at regular intervals, looking at all files that may need to be reorganized, but only reorganize the ones that really need it.
See the Technical Detail page for an example of FDRREORG job to re-organize VSAM files.
Handling PDSs with FDRREORG
PDS data sets also require special attention, but the standard utility IEBCOPY lacks the intelligence and performance to deal with PDSs in large numbers:
Like an IEBCOPY compress-in-place, FDRREORG compresses PDS data sets by placing all active members to the beginning of the PDS to allow room for new members to be added.
FDRREORG can be transparently invoked, without modification to the operating system, so that when IEBCOPY is called to compress PDS data sets, FDRREORG takes over and completes the task.
See the Technical Detail page for an example of FDRREORG job to compress PDSs.
Simulation & Reporting
A simulation mode is provided with FDRREORG to allow you to test and verify your selection criteria. before running a VSAM Re-Organization or PDS Compression. The simulation report shows exactly which files would have been selected if the process were run for real.
After an execution of a “real” FDRREORG, a summary report like the one shown below is produced to show which files were selected for processing, together with information about their before/after status:
Moving & Consolidating VSAM
FDRREORG can move or consolidate multi-volume VSAM files from one location to another – e.g. a VSAM file spread over several 3390-3s can be consolidated onto a single 3390-9 with FDRREORG.
However, for more general information on consolidating DASD (e.g. moving from 3390-3s to 3390-9s) see FDRMOVE.
For more introductory information on FDRREORG, see the Product Portfolio Sheet
For JCL examples of FDRREORG, see the Technical Detail section.
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