Planning for maintenance

In designing your database, remember to plan for maintenance. If your applications require, for instance, that the database be available 16 hours a day, you do not design a database that takes 10 hours to unload and reload.

No guideline we can give you for planning for maintenance exists, because all such plans are application dependent. However, remember to plan for it.

A possible solution to the problem just described is to make three separate databases and put them on different volumes. If the separate databases have different key ranges, then application programs could include logic to determine which database to process against. This solution would allow you to reorganize the three databases at separate times, eliminating the need for a single 10-hour reorganization. Another solution to the problem if your database uses HDAM or HIDAM might be to do a partial reorganization using the Partial Database Reorganization utility.

In the online environment, the Image Copy utilities allow you to do some maintenance without taking the database offline. These utilities let you take image copies of databases or partitions while they are allocated to and being used by an online IMS system.

HALDB provides greatly improved availability for large databases. By partitioning large databases, you can perform offline maintenance on a single partition, while the remaining partitions remain available.

You can also reorganize HALDB databases online, which improves the performance of your HALDB without disrupting access to its data. If you plan to reorganize your HALDB online, make sure that there is enough DASD space to accommodate the reorganization process.