It's inevitable that you see a couple of DB2 fix packs every year and place the readme document in a drawer somewhere for perusal later when you are not busy. While the fix packs may contain fixes there are sometimes a few enhancements buried in the fine print.
With large tablespaces, well designed NPIs can improve query performance but can create performance and availability challenges. DPSIs can help, but have their own compromises. In this article, Toine Michielse provides an overview of some DPSI-related enhancements coming in DB2 11 for z/OS.
In this article Jeff Lane presents a real life situation in which parallelism presented a performance dilemma. Do you tune for response time or reduced cost?