Re: high io BUT huge amount of free memory

On Mon, Apr 22, 2013 at 1:22 PM, Миша Тюрин <tmihail(at)bk(dot)ru> wrote:
>
> My first message has been banned for too many latters.
>
>>
> Hi all
> There is something wrong and ugly.
>
> 1)
> Intel 32 core = 2*8 *2threads
>
> Linux avi-sql09 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
>
> 24*128GB HDD (RAID10) with 2GB bbu (1,5w+0,5r)
>
> 2)
> free -g
> total used free shared buffers cached
> Mem: 378 250 128 0 0 229
> -/+ buffers/cache: 20 357
>
> 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)
>
> 3) so maybe I've got something like this
> http://www.databasesoup.com/2012/04/red-hat-kernel-cache-clearing-issue.html
> or this
> http://comments.gmane.org/gmane.comp.db.sqlite.general/79457
>
> 4) now i think
> a) upgrade linux core or
> b) set buffers to something like 300-320Gb
> my warm work set is about 300-400GB
> db at all - 700GB
>
> typical work load - pk-index-scans
>
> --
> looking forward
> thanks

this topic is more suitable for -performance.

check out this:

http://frosty-postgres.blogspot.com/2012/08/postgresql-numa-and-zone-reclaim-mode.html

merlin