Re: How to tune for "too many" users ?

Hi Jan,
Giving advices with this little knowledge of your application or environment is very difficult even hazardous. Make sure you understand the modifications prior to trying them to production.

> db_block_buffers 30000
> sort_area_size 640000

I noticed these two parameters. You did not tell the size of your server's RAM, but these seem quite small.  From my experience, commonly performance problems are related to memory issues. One may either have too small buffer cache (db_block_buffers x db_block_size) and too much of data has to be fetched from the disks instead of memory OR in some cases Oracle's memory consumption may be too large causing swapping in the OS.

Previously Norman Dunbar suggested Statspack. I agree, you definitely should install it (by running script
$ORACLE_HOME/rdbms/admin/spcreate.sql). To get any relevant data, I recommend taking two snapshots (sqlplus> exec statspack.snap) when the actual problem situation is going on for instance when the system is slow. Have the time between snapshots as short as possible, about 10 seconds might be a goot start. And then run the report between those two snapshots ($ORACLE_HOME/rdbms/admin/spreport.sql). The interpreting of the report may be tricky and as told, the oraperf.com can help in there.

Another issue is the OS. What is the bottleneck in there? Is it the processors, memory, disk IO or the network? In your AIX system you have tools like vmstat, iostat and topas. However those are out of this posts scope.

Hopefully this helped :-)

--
Sami Tillgren