"J.T. Hartzler" <dba@wap.ntelos.com> writes:
> Based on what I read in the docs I should be able to use at
> setting of shared_buffers = 454000 in my postgresql.conf file as I want
> to use about 3600MB of memory for my database.
This is a bad idea in any case, even if your kernel would let you do it.
Try configuring a couple thousand shared_buffers to start out with.
You can find lots of discussion of this topic in the archives, but the
key point is that kernel disk cache is a perfectly effective use of RAM.
You don't need to, and shouldn't try to, make Postgres buffers occupy
all of RAM, or even a very large percentage of it.
regards, tom lane