logbufsz - Log buffer size configuration parameter

This parameter allows you to specify the amount of the database heap (defined by the dbheap parameter) to use as a buffer for log records before writing these records to disk.

Configuration type
Parameter type
  • Configurable
  • Configurable by member in a Db2® pureScale® environment
Default [range]
32-bit platforms
256 [4 - 4 096 ]
64-bit platforms
256 [4 - 131 070 ]
Note: The default value is subject to change by the Db2 Configuration Advisor after initial database creation.
Unit of measure
Pages (4 KB)
Log records are written to disk when one of the following occurs:
  • A transaction commits or a group of transactions commit, as defined by the mincommit configuration parameter
  • The log buffer is full
  • As a result of some other internal database manager event.

This parameter must also be less than or equal to the dbheap parameter. Buffering the log records will result in more efficient logging file I/O because the log records will be written to disk less frequently and more log records will be written at each time.

Recommendation: Increase the size of this buffer area if there is considerable read activity on a dedicated log disk, or there is high disk utilization. When increasing the value of this parameter, you should also consider the dbheap parameter since the log buffer area uses space controlled by the dbheap parameter.

You can use the database system monitor to determine how often the log buffer has become full, requiring it to be written to disk before new log records can be written. Refer to the num_log_buffer_full (number of full log buffers) monitor element.