Message-ID: <4DBE38BB.7040106@orkash.com>
Date: Mon, 02 May 2011 10:23:15 +0530
From: Adarsh Sharma <adarsh.sharma@orkash.com>
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To: pgsql-performance@postgresql.org
Subject: Re: The right SHMMAX and FILE_MAX
References: <BANLkTinCr_+Hs_zzHPb+tBdtuLFhrsfKdg@mail.gmail.com>
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I am also in need of a proper documentation that explains how to set  
SHMAX and SHMALL variables in Postgres.

What things need to be taken in consideration before doing that ?
What is the value of SHMAX & SHMALL if u have 16 GB RAM for Postgres 
Server ?


Thanks

Phoenix Kiula wrote:
> Hi. I'm on a 64 Bit CentOS 5 system, quadcore processor, 8GB RAM and
> tons of data storage (1 TB SATAII disks).
>
> The current SHMMAX and SHMMIN are (commas added for legibility) --
>
> kernel.shmmax = 68,719,476,736
> kernel.shmall = 4,294,967,296
>
> Now, according to my reading in the PG manual and this list, a good
> recommended value for SHMMAX is
>
>    (shared_buffers * 8192)
>
> My postgresql.conf settings at the moment are:
>
>     max_connections = 300
>     shared_buffers = 300MB
>     effective_cache_size = 2000MB
>
> By this calculation, shared_b * 8192 will be:
>
>      2,457,600,000,000
>
> That's a humongous number. So either the principle for SHMMAX is
> amiss, or I am reading this wrongly?
>
> Similarly with "fs.file_max". There are articles like this one:
> http://tldp.org/LDP/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3/chap6sec72.html
>
> Is this relevant for PostgreSQL performance at all, or should I skip that?
>
> Thanks for any pointers!
>
>