Change of topic...
Those of you who have dealt with Sun storage performance over the years might have heard of Dave Fisk, we became good friends when I worked together with him in the same group many years ago, then he went to work for the Sun storage business unit, and finally he left Sun to build a storage performance analysis product. After a lot of work over several years he has finally got his product ready, and it cracks open the storage stack so you can see what is really happening.
Dave's company is called ORtera and they have a downloadable beta release available which you can get a free one month evaluation license for.
If you ever wondered why the I/O traffic your application (e.g. Oracle) is generating don't seem to match up with the stats you see in iostat, then this tool will show you why. For example, small filesystem writes can cause larger read-modify-write operations to occur and the tool will show you this, point it out with a heuristic and suggest a filesystem tuning fix.
Its a useful addition to the toolbox, I think they should have called it "virtual Dave" :-)