Sounds like you were really trying to optimize for the top 0.1% :) I think you have hinted that you can't simply "turn on" O_DIRECT and have magic happen and if

Sounds like you were really trying to optimize for the top 0.1% :) I think you have hinted that you can't simply "turn on" O_DIRECT and have magic happen and if O_DIRECT is not used with a proper tune, you will be in more trouble. The irony with my story is that even with the horrible DB2 config our "guru" DBA's left us with, all the issues were from the software team. There were many stupid things going on in the ORM that were causing the issues (like grabbing an entire table and then calling a method on each row that in turn got a aggregate sum of a column on the same table... doing that for each row).