If you send backup to disks, you should have a separate directory for automatic maintenance backups. DB2 will automatically prune backup images, so, if you scheduled backups via the task center or other tools such as cron or other manual backups, make sure to save them in another directory, otherwise they will be deleted.

If you select an online backup and the database is configured with circular logging, DB2 will offer to change this and will do an online backup right away. Automatic backups results will be sent to db2diag.log. There are more advanced methods for backups; we will cover these in Chapter 7, DB2 Backup and Recovery.

DB2 Reorgs defragment table and index data. Automatic reorgs, before DB2 v9.7, were done in place. You needed to have enough space for a table and its copy on the same table space and could not tell DB2 to use a temporary table space. In DB2 v9.7, you now need to have a system temporary table space large enough for the largest table.

Reorg results are sent to db2diag.log.

The Runstats utility gathers table and index statistics and information for the SQL optimizer. DB2 uses this information for its optimizer, and chooses the best path for each SQL query. With the automatic maintenance, you don't have to worry about being notified by development about new tables, and indexes, since they'll all be picked up for runstats (depending on the table scope you selected).

There is a downside to this. This utility is useful for small tables, since statistics are collected on the whole table. For large tables several Gigabytes in size, this could generate problems. You can override the default statistics settings for a table by setting a statistics profile. We'll discuss this in Chapter 13, DB2 Tuning and Optimization.

Runstat results are sent to db2diag.log.