From: Kevin Grittner <kgrittn@ymail.com>
To: ac@hsk.hk <ac@hsk.hk>
To: Josh Krupka <jkrupka@gmail.com>
To: Johnny Tan <johnnydtan@gmail.com>
Cc: Alex Kahn <alex@paperlesspost.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: postgresql.conf recommendations
Date: Wed, 6 Feb 2013 04:49:47 -0800 (PST)
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"ac@hsk.hk" <ac@hsk.hk> wrote:
> Johnny Tan <johnnydtan@gmail.com> wrote:
>>shared_buffers = 48GB# min 128kB
> From the postgresql.conf, I can see that the shared_buffers is
> set to 48GB which is not small, it would be possible that the
> large buffer cache could be "dirty", when a checkpoint starts, it
> would cause a checkpoint I/O spike.
>
>
> I would like to suggest you about using pgtune to get recommended
> conf for postgresql.
I have seen symptoms like those described which were the result of
too many dirty pages accumulating inside PostgreSQL shared_buffers.
It might be something else entirely in this case, but it would at
least be worth trying a reduced shared_buffers setting combined
with more aggressive bgwriter settings. I might try something like
the following changes, as an experiment:
shared_buffers = 8GB
bgwriter_lru_maxpages = 1000
bgwriter_lru_multiplier = 4
-Kevin
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Cc: kgrittn@ymail.com, ac@hsk.hk, jkrupka@gmail.com, johnnydtan@gmail.com, alex@paperlesspost.com
Subject: Re: postgresql.conf recommendations
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