Oracle tuning: Examining the Oracle instance

Good articles on tuning, just one remark: We tend to begin with looking at the slowest-application compoents (indicated by users, or batches) and from that we first examine the worst stmnts and then the program logic. Often, that yields fast + good results. Only then do we start "holistic" tuning by examining the whole system, server, database, instnance etc... The main idea is to catch the biggest programmer-gaps first.

Testing the querys in the tuning article, what do the reads, consistant gets etc mean. Meaning, how do I decide whether they are showing good performance or bad? Not sure what they constitute.

This is a dangerous parameter. It would be fine if Oracle decided to do a table scan and then used the paramter to determine how many blocks it reads but it uses the paramter to decide to do a table scan and if it is set too high all you get is table scans. This can be a disaster when you run out of memory.