[presumably the empty-disk effect could also be achieved by partitioning, say
25% of the drive for the database, and 75% empty partition. But in fact, you
could use that "low performance 75%" for rarely-used or static data, such as
the output from pg_dump, that is written during non-peak times]
You don't mention the capacity of the disks you are looking at. Here is
something you might want to consider.
I've seen a few performance posts on using different hardware
technologies to gain improvements. Most of those comments are on raid,
interface and rotation speed. One area that doesn
