We have an openSUSE 11.2 machine running PostgreSQL 8.4.2 that we
recently upgraded from 24 to 74G RAM. We have a single swap partition
of 2G that free tells us is completely used. I don't see any swap IO
when I run vmstat at reasonably busy points in the day (although it
must happen some time... perhaps during nightly dumps) . Other than
all swap used this looks good:
total used free shared buffers cached
Mem: 74372840 74154700 218140 0 198732 68919724
-/+ buffers/cache: 5036244 69336596
Swap: 2104444 2104444 0
Is there some minimum proportion of swap to physical memory that linux
or postgresql likes to have? Is it OK for all
Usage: this machine hosts a cluster of three databases, one which
dominates the activity. We have during the day 900-1000 connections,
approximately 100 of which are pumping data in via libpq copy, most
other connections send infrequent small queries. There will
frequently be one or two big queries going on (peg a core, use lots of
IO for up to several minutes). Pgdump at night, several in parallel
handling different portions of our database.
Responsiveness of the database and it's ability to absorb the
significant data we throw at it is quite good, I have no reason to
suspect anything is wrong other than that I've never seen all swap
used on a linux machine before.
I believe my mem settings are modest for a machine like this:
shared_buffers=5GB, work_mem=32MB, maintenance_work_mem=1GB.
Should I be concerned?
Thanks,
-K