Administration Guide

Additional Space Requirements

Additional space is also required for:

• Log File Space
• Temporary Work Space

Log File Space

The amount of space (in bytes) required for log files can range from:

   ( logprimary * (logfilsiz + 2 ) * 4096 ) + 8192

to:

   ( (logprimary + logsecond) * (logfilsiz + 2 ) * 4096 ) + 8192

where:

• logprimary is the number of primary log files, defined in the database configuration file
• logsecond is the number of secondary log files, defined in the database configuration file
• logfilsiz is the number of pages in each log file, defined in the database configuration file
• 2 is the number of header pages required for each log file
• 4096 is the number of bytes in one page
• 8192 is the size (in bytes) of the log control file.

Refer to the Administration Guide: Performance for more information about these configuration parameters.

Note:

The total active log space cannot exceed 32 GB.

The upper limit of log file space is dependent on the actual number of secondary log files that the database manager requires at run time. This upper limit may never be required, or may be needed only during occasional periods of high volume activity.

If the database is enabled for roll-forward recovery, special log space requirements should be taken into consideration:

• With the logretain configuration parameter enabled, the log files will be archived in the log path directory. The online disk space will eventually fill up, unless you move the log files to a different location.
• With the userexit configuration parameter enabled, a user exit program moves the archived log files to a different location. Extra log space is still required to allow for:
  • Online archived logs that are waiting to be moved by the user exit program
  • New log files being formatted for future use.

Temporary Work Space

Some SQL statements require temporary tables for processing (such as a work file for sorting operations that cannot be done in memory). These temporary tables require disk space; the amount of space required is dependent upon the queries, and the size of returned tables, and cannot be estimated.

You can use the database system monitor and the query table space APIs to track the amount of work space being used during the normal course of operations.