Date: November 30, 2001
The default AIX tuning parameters are not always optimal. I recently reran an Oracle 8.1.7 benchmark using the default AIX 4.3.3 settings and was very suprised to find that the tuned system had roughly twice the throughput compared to the default AIX settings.
In this case, the key tuning parameters were vmtune's maxpgahead and numfsbufs. The maxpgahead improved sequential I/O in the JFS filesystem. The numfsbufs relieved I/O contention by increasing the number of filesystem buffers. The final tuning parameters are listed at:
So, if you are having performance issues, and are using the default AIX settings, there's a good chance tuning will help.
(Standard Disclaimer: "Your mileage may vary.")