Received: from localhost (unknown [200.46.204.183])
	by postgresql.org (Postfix) with ESMTP id 9C7C1650190
	for <pgsql-performance-postgresql.org@postgresql.org>;
	Mon,  8 Sep 2008 12:17:46 -0300 (ADT)
Received: from postgresql.org ([200.46.204.86])
	by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024)
	with ESMTP id 39990-07 for
	<pgsql-performance-postgresql.org@postgresql.org>;
	Mon,  8 Sep 2008 12:17:43 -0300 (ADT)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6
Received: from wa-out-1112.google.com (wa-out-1112.google.com
 [209.85.146.180])
	by postgresql.org (Postfix) with ESMTP id 19FC965018B
	for <pgsql-performance@postgresql.org>;
	Mon,  8 Sep 2008 12:17:42 -0300 (ADT)
Received: by wa-out-1112.google.com with SMTP id n4so1333480wag.5
	for <pgsql-performance@postgresql.org>;
	Mon, 08 Sep 2008 08:17:42 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma;
	h=domainkey-signature:received:received:message-id:date:from:to
	:subject:cc:in-reply-to:mime-version:content-type:references;
	bh=7YDP3bI/m0/36PKXuDPF+Mixc+pS5y5K31nyzIiDOaM=;
	b=WSmIRtxXCoQYW1mq9PS2/+mCmpz90SozhjPe4JNgMzbiZBDTavkdLI9ZDbbxPO98QX
	aAdqY6/Gw8nPyYhOYSLEnpXRUJ4nmtqaomvnTCWfa+0iM81zmaO+8vyrwByS7G57oRiU
	uEkKneALZk/AxOVprIMKtz6I7RvvlIUXVICHQ=
DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma;
	h=message-id:date:from:to:subject:cc:in-reply-to:mime-version
	:content-type:references;
	b=F8Kkyg1n8a0pxkebQNJAA0IOLNAeUqHVSvYbyYB9JCrYm4YmFUGvUqhn9yHxXe98C/
	I5L4/5RQVbmEKsY1WVCdn3dAO+7VbZo5cNsoI6KThstXecQIEGi0om8Pe1qFMiai0fHZ
	RavgNFOpmTtNavPdC5FqJ88v/WlTHdh34GpyE=
Received: by 10.114.191.12 with SMTP id o12mr12443294waf.224.1220887061878;
	Mon, 08 Sep 2008 08:17:41 -0700 (PDT)
Received: by 10.114.120.19 with HTTP; Mon, 8 Sep 2008 08:17:41 -0700 (PDT)
Message-ID: <d4e11e980809080817l4f29c647s2e4485451c5e62c1@mail.gmail.com>
Date: Mon, 8 Sep 2008 11:17:41 -0400
From: "Nikolas Everett" <nik9000@gmail.com>
To: "Gregory Stark" <stark@enterprisedb.com>
Subject: Re: SAN and full_page_writes
Cc: "Bruce Momjian" <bruce@momjian.us>, pgsql-performance@postgresql.org
In-Reply-To: <873aka4rbc.fsf@oxford.xeocode.com>
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----=_Part_57681_32297159.1220887061848"
References: <d4e11e980809050724m5f0e8971n3909c26026fda47b@mail.gmail.com>
	<200809061946.m86JkeS01341@momjian.us>
	<d4e11e980809080702i629187bbqab5dd70581ee8057@mail.gmail.com>
	<87myii4t9o.fsf@oxford.xeocode.com>
	<d4e11e980809080748k6f647b6cue9d202f8feb9abca@mail.gmail.com>
	<873aka4rbc.fsf@oxford.xeocode.com>
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Spam-Status: No, hits=0.001 tagged_above=0 required=5
	tests=HTML_MESSAGE=0.001
X-Spam-Level: 
X-Archive-Number: 200809/87
X-Sequence-Number: 31400

------=_Part_57681_32297159.1220887061848
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

On Mon, Sep 8, 2008 at 10:59 AM, Gregory Stark <stark@enterprisedb.com>wrote:

>
> That "media recovery" it's referring to sounds like precisely our WAL full
> page writes...
>
>
> --
>   Gregory Stark
>  EnterpriseDB          http://www.enterprisedb.com
>   Ask me about EnterpriseDB's PostGIS support!
>

That sounds right.

So the take home from this is that NetApp does its best to protect you from
partial page writes but comes up short on untweaked NFS (see doc to tweak.)
Otherwise you are protected so long as your OS and file system implement
fsync properly.

--Nik

------=_Part_57681_32297159.1220887061848
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

<div dir="ltr">On Mon, Sep 8, 2008 at 10:59 AM, Gregory Stark <span dir="ltr">&lt;<a href="mailto:stark@enterprisedb.com">stark@enterprisedb.com</a>&gt;</span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
That &quot;media recovery&quot; it&#39;s referring to sounds like precisely our WAL full<br>
page writes...<br>
<br>
<br>
--<br>
<div class="Ih2E3d"> &nbsp;Gregory Stark<br>
 &nbsp;EnterpriseDB &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<a href="http://www.enterprisedb.com" target="_blank">http://www.enterprisedb.com</a><br>
</div> &nbsp;Ask me about EnterpriseDB&#39;s PostGIS support!<br>
</blockquote></div><br>That sounds right.<br><br>So the take home from this is that NetApp does its best to protect you from partial page writes but comes up short on untweaked NFS (see doc to tweak.)&nbsp; Otherwise you are protected so long as your OS and file system implement fsync properly.<br>
<br>--Nik<br></div>

------=_Part_57681_32297159.1220887061848--