Space Management with DB2 UDB for UNIX and Windows

Purpose

This section looks at space management (including reorganization) of database objects (that is, tables and table spaces). If you neglect space management, this can lead to downtime due to normal database growth when database objects fill up. If this happens, applications cannot write to the database and you have to quickly make more space available. Therefore, it is much better to anticipate the problem by monitoring and pro-actively managing the disk space in your database.

We recommend you to manage space on your DB2 database using the Computing Center Management System (CCMS) in the SAP system. You need to monitor regularly and take timely action to avoid the problem leading to downtime.

Prerequisites

The standard page size for DB2 UDB for UNIX and Windows is 4 KB. This leads to a limitation of 64 GB per table space. If larger table spaces are needed, DB2 UDB for UNIX and Windows offers the additional pages sizes 8 KB, 16 KB, and 32 KB.

Table space limitations

Page size of table space

Maximum table space size

4 KB

64 GB

8 KB

128 GB

16 KB

256 GB

32 KB

512 GB

Process Flow

...

       1.      You monitor storage by using CCMS.

If free space in a table space decreases continuously, extend the table space by resizing or adding containers or by reorganizing tables. Resizing containers is the fastest way to extend table spaces.

       2.      When free space in a table space reaches a critical limit, you decide which of the following to do:

Ў        Manage table spaces

Ў        Manage tables and indexes

Result

By managing the space in your DB2 UDB for UNIX and Windows database, you can avoid unplanned downtime due to database objects filling up.