Performance on SUSE w/ reiserfs

I have a SUSE 9 box that is running Postgres 8.0.1 compiled from source.
Over time, I see the memory usage of the box go way way up (it's got
8GBs in it and by the end of the day, it'll be all used up) with what
looks like cached inodes relating to the extreme IO generated by
postgres. We replicate about 10GBs of data every day from our AS/400
into postgres, and it is the main database for our intranet portal,
which will server 40,000 pages on a good day.

I was wondering if there is something I'm doing wrong with my default
settings of postgres that is keeping all that stuff cached, or if I just
need to switch to XFS or if there is some setting in postgres that I can
tweak that will make this problem go away. It's gone beyond an annoyance
and is now into the realm of getting me in trouble if I can't keep this
DB server up and running. Even a minute or two of downtime in a restart
is often too much.

Any help you can give in this would be extrememly helpful as I'm very
far from an expert on Linux filesystems and postgres tuning.

Thanks!

--

Jon Brisbin
Webmaster
NPC International, Inc.