The database engine reads and writes information to the BI file in blocks. Increasing the size of these blocks allows the engine to read and write more data at one time. This can reduce I/O rates on disks where the BI files are located.

The default BI block size (8K) is sufficient for applications with low transaction rates. However, if performance monitoring indicates that BI writes are a performance bottleneck and your platform's I/O subsystem can take advantage of larger writes, increasing the BI block size might improve performance.

To change the BI block size:

  1. Use the PROSHUT command or the PROMON Shutdown a Database option to shut down the database.
  2. To change the BI block size, use the PROUTIL TRUNCATE BI command, as shown: command: 
     proutil db-name -C truncate bi -biblocksize size

    For size, specify the new BI block size in kilobytes. Valid values are 0, 1, 2, 4, 8, and 16.

    You can also change the BI cluster size with this command. You might want to do so at this time. For more information, see Increase the BI cluster size.

    For detailed information on this command, see PROUTIL Utility.