Kevin,
> # maintenance_work_mem = 256MB #webserver with 2GB RAM
Well, that was before multiple autovacuum workers. Now, you'd want it
lower. But ... it's better for vacuum to finish quickly than to drag
on. Vacuum uses more I/O than it does RAM.
> But I'm amazed by this, too:
>
> # max_connections = 700 # web application database
>
> How many CPUs and spindles are you assuming there?
I'm assuming that the user isn't using connection pooling, and 7/8 of
those connections will be idle at any given time.
--Josh