Unload and reload function overview

• Use the UNLOAD command to unload one or more areas from a DEDB to formats that are compatible with any of the following:

  • IBM HD Reorganization Unload utility

  • IBM MSDB maintenance utility

  • IBM Fast Path Basic Tools for z/OS DEDB Reload utility

  • BMC TRIMAR FAST PATH UNLOAD/RELOAD product

• Use the RELOAD command to load one or more areas of a DEDB from input in any of the supported unload formats

The UNLOAD command can be used to produce an unload file to be processed later by the IBM HD Reorganization Reload Utility. For example, the file can be used to create an HDAM database for BTS testing. You can also use the unload/reload functions to convert between DEDBs and Main Storage Databases (MSDBs). For additional compatibility with legacy application programs, the UNLOAD command can be used to produce a TRIMAR unload format or IBM DBT unload format.

If you have created an index or indexes to the DEDB by using the BMC Fast Path Indexer/EP product, you can rebuild any and all indexes registered for the DEBD at the same time the reload function is performed.

When you need to modify the data content of a segment, you can accomplish it in two ways. The DEDB change function and the unload/reload functions allow segment data to be modified by using the OUTPUT subcommand. If more extensive changes are required, the UNLOAD command can be used to create an unload file. You can then use program extensions FABEUR7 and FABEUR6 to make changes to the data. Changed data is then used as input to the RELOAD command.

The DEDB change function restructures a DEDB by reading the DEDB, and writing the restructured DEDB directly to DASD. Because this method does not require separate unload and reload steps, it is the most efficient way to restructure a DEDB if sufficient DASD resources are available.

Because the Fast Path/EP reorganization function does not require separate unload and reload steps, it is the most efficient way to reorganize a DEDB to reclaim free space without making structure changes. It can also be used to extend the space that is allocated to the IOVF and SDEP portions of the area.