Alex,
In the situation of the animal hospital server I oversee, their
application is OLTP. Adding hard drives (6-8) does help performance.
Benchmarks like pgbench and OSDB agree with it, but in reality users
could not see noticeable change. However, moving the top 5/10 tables and
indexes to their own space made a greater impact.
Someone who reads PostgreSQL 8.0 Performance Checklist is going to see
point #1 add more disks is the key. How about adding a subpoint to
explaining when more disks isn't enough or applicable? I maybe
generalizing the complexity of tuning an OLTP application, but some
clarity could help.
Steve Poe
