Speeding up DB/Reorg

Products

• IDMS

Issue/Introduction

Using DB/Reorg, program USRDRVR, what are some ways to speed up performance of the DB/REORG utility?

Environment

Release: All supported releases.
Component: Reorg.

Resolution

Regarding DB/REORG performance, there are many ways you can improve the DB/REORG job execution time: 

AREA SIZE: 
If this is a very large REORG, run the REORG by area. REORG execution time is directly related to the size of the areas, number of records in the areas and the number of set linkages for these records. The jobs can also be run step by step, although this will not reduce the overall time it will allow them to break up the job into perhaps more manageable time portions. 

INDEX SR8 records. 
If there are many SR8 Index records, DB/REORG can rebuild them however MAINTAIN INDEX may be faster. On the other hand, if the DB/REORG is reorganizing an index set sorted by db-key, or an area containing integrated index sets sorted by db-key, these areas have to be included in the PROCESS statement, COPY AREA setting.

SYSIDMS PREFETCH 
DB/REORG does utilize the PREFETCH parameter for read-ahead processing.

Lastly, when executing DB/REORG ensure that no CV or local update jobs are accessing the database as DB Reorg will not attempt to run against an area locked for update.

Additional Information

IDMS/DB Reorg Database Access