DB2 Infinite Active Log Space

In DB2, when a database is created, 3 log files are allocated. They are known as primary log files. In Linux/Unix environment, they will be 1000 * 4K pages for each log file by default, whereas in Windows it is 250 * 4k pages.

By default, up to two secondary log files will be created if needed, and their size will equal that of each primary log file used. However, the total number of secondary log files allowed is also configurable (via the logsecond database configuration parameter).

You might think you can avoid running out of log space by configuring a database to use a large number of secondary log files. However, the maximum number of secondary log files allowed is 254. If the size of your log files is relatively small, you can still run out of log space quickly when transaction workloads become heavy. You should avoid allocating a large number of secondary log files, if possible, because performance is affected each time a log file has to be allocated. Ideally, you should allocate enough primary log files to handle most situations, then use just enough secondary log files to handle peak times in transaction workloads. If you're concerned about running out of log space and want to avoid allocating a large number of secondary log files, you can configure a database to use what is known as infinite logging. To enable infinite logging, simply set the database configuration parameters userexit and logsecond to YES and -1, respectively.