Configuration Issue ?

Hi

Please help. I have got a postgres 7.3.4 database running on RedHat ES
3, with 8GB of physical memory in it. The machine is shared with my
application which is pretty intensive in doing selects and updates
against the database, but there are usually no more than 10 connections
to the database at any time.

Despite having 8GB of RAM on the machine, the machine is frequently
running out of physical memory and swapping which is hurting
performance. Have read around on various of the message boards, and I
suspect that the SHARED_BUFFERS setting on this server is set way to
high, and that this in fact may be hurting performance. My current
configuration settings are as follows:

shared_buffers = 393216 # min max_connections*2 or 16, 8KB each

max_fsm_relations = 10000 # min 10, fsm is free space map, ~40
bytes

max_fsm_pages = 160001 # min 1000, fsm is free space map, ~6

bytes

sort_mem = 409600 # min 64, size in KB

vacuum_mem = 81920 # min 1024, size in KB

From what Ive read, Ive not seen anyone recommend a SHARED_BUFFERS
setting higher than 50,000. Is a setting of 393216 going to cause
significant problems, or does this sound about right on an 8GB system,
bearing in mind that Id like to reserve at least a couple of GB for my
application.

Also if you have any recommendations regarding effective_cache_size Id
be interested as reading around this sounds important as well

Thanks

Mark