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Date: Wed, 23 Oct 2013 22:57:57 +0200
From: Michael Schmiedgen <schmiedgen@gmx.net>
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To: Mark Felder <feld@FreeBSD.org>, Albert Shih <Albert.Shih@obspm.fr>, 
 pgsql-admin@postgresql.org, freebsd-fs@freebsd.org, 
 freebsd-jail@freebsd.org
Subject: Re: ZFS-FreeBSD + postgresql performance
References: <20131023162545.GA19794@pcjas.obspm.fr>
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On 10/23/13 19:14, Mark Felder wrote:
> On Wed, Oct 23, 2013, at 11:25, Albert Shih wrote:
>> My question is about the performance, I known ZFS eat all memory he can
>> have (or almost), so what append when we run database like postgresql and
>> jail ? (it's also the reason of 96 Go ram).
>>
>> Sorry for cross-posting but it's about 3 differents things....
>>
>
> To my understanding the solution is to change the primarycache to
> "metadata" for any ZFS filesystem that you do not want ZFS to heavily
> cache in memory.
>
> Example:
>
> # zfs set primarycache=metadata tank/usr/local/pgsql

In addition to this it is recommended to set the recordsize
to the fixed value of 8k on dataset creation.

Michael