Changing direct-access storage devices

Several situations might warrant tuning your database by changing DASDs (direct-access storage devices).

First, when application requirements change, you might require a faster or slower device. Second, you might want to take advantage of new devices offering better performance. Finally, you might need to change devices to get database data sets on two different devices, so as to minimize contention for device use.

You can change your database (or part of it) from one device to another using the reorganization utilities. To change direct-access storage devices:

Procedure

  1. Unload your database using the existing DBD and the appropriate unload utility.
  2. Recalculate CI or block size to maximize use of track space on the new device.
  3. Code a new DBD.
  4. For non-VSAM data sets, delete the old database space and define new database space. For VSAM data sets, delete the space allocated for the old clusters and define space for the new clusters.
  5. Reload your database, using the new DBD and the appropriate reload utility. Remember to make an image copy of your database as soon as it is reloaded.
  6. If your database uses logical relationships or secondary indexes, you must run reorganization utilities before and after reloading the database to resolve prefix information.