Re[2]: [HACKERS] high io BUT huge amount of free memory

thanks a lot for responses

1) just remind my case

Intel 32 core = 2*8 *2threads
Linux 2.6.32-5-amd64 #1 SMP Sun May 6 04:00:17 UTC 2012 x86_64 GNU/Linux
PostgreSQL 9.2.2 on x86_64-unknown-linux-gnu, compiled by gcc-4.4.real (Debian 4.4.5-8) 4.4.5, 64-bit
shared_buffers 64GB / constant hit rate - 99,18
max_connections 160 / with pgbouncer pools there could not be more than 120 connections at all
work_mem 32M
checkpoint 1h 1.0
swap off
numa off, interleaving on
and
! disks usage 100% (free 128GB! WHY?)
disk throughput - up-to 30MB/s (24r+6w)
io - up-to 2,5-3K/s (0,5w + 2-2,5r)
typical work load - pk-index-scans
my warm work set is about 400GB
db at all - 700GB

2) numactl
mtyurin(at)avi-sql09:~$ numactl --hardware
available: 1 nodes (0-0)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
node 0 size: 393181 MB
node 0 free: 146029 MB
node distances:
node 0
0: 10

3) !! i just found suspicious relation between "active" processes and free memory. ~1GB per process.
in 376GB total memmory and 32 core
if ( user cpu + io wait ) is ~140% then i have ~140GB free.
but it could be just a coincidence.

4) now i think
a) upgrade linux core (to 3.2!?) and then (if case still will be)
b) set buffers to something like 300-320Gb

5) what do you know about workload in Berkus's case http://www.databasesoup.com/2012/04/red-hat-kernel-cache-clearing-issue.html ?