From: Mark Felder <feld@FreeBSD.org>
To: Albert Shih <Albert.Shih@obspm.fr>
To: pgsql-admin@postgresql.org
To: freebsd-fs@freebsd.org
To: freebsd-jail@freebsd.org
Subject: Re: ZFS-FreeBSD + postgresql performance
Date: Wed, 23 Oct 2013 12:14:25 -0500
Message-ID: <1382548465.32073.37624113.6AA8DB42@webmail.messagingengine.com> (raw)
In-Reply-To: <20131023162545.GA19794@pcjas.obspm.fr>
References: <20131023162545.GA19794@pcjas.obspm.fr>
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On Wed, Oct 23, 2013, at 11:25, Albert Shih wrote:
> Hi
>
> I would like to known if someone here have in production a FreeBSD server
> with postgresql and the FS for the data of postgresql is a ZFS pool.
>
> I'm going to buy some server with 96Go of Ram and a jbod of 12 disks (4To
> each)
>
> The purpose is to have everything on this zfs pool (except the system who
> still on classic raid). So to have
>
> many jail (~20-30) running apache/mysql/etc.
> one postgresql server with all data on the zfs.
>
> each jail use his own zfs partition. So I can use zfs send/received to
> have
> a mirror of everything in a other server.
>
> 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
Now for my ZFS filesystem "tank/usr/local/pgsql" where the postgres data
directory exists we will tell ZFS to only cache metadata there. Postgres
will do its own caching of the data.
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To: pgsql-admin@postgresql.org
Cc: feld@FreeBSD.org, Albert.Shih@obspm.fr, freebsd-fs@freebsd.org, freebsd-jail@freebsd.org
Subject: Re: ZFS-FreeBSD + postgresql performance
In-Reply-To: <1382548465.32073.37624113.6AA8DB42@webmail.messagingengine.com>
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