From owner-freebsd-fs@FreeBSD.ORG  Fri Feb 20 11:46:45 2015
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
Delivered-To: freebsd-fs@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id B95AECAE
 for <freebsd-fs@freebsd.org>; Fri, 20 Feb 2015 11:46:45 +0000 (UTC)
Received: from forward5l.mail.yandex.net (forward5l.mail.yandex.net
 [IPv6:2a02:6b8:0:1819::5])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "forwards.mail.yandex.net",
 Issuer "Certum Level IV CA" (verified OK))
 by mx1.freebsd.org (Postfix) with ESMTPS id 71BCDD3C
 for <freebsd-fs@freebsd.org>; Fri, 20 Feb 2015 11:46:45 +0000 (UTC)
Received: from smtp16.mail.yandex.net (smtp16.mail.yandex.net [95.108.252.16])
 by forward5l.mail.yandex.net (Yandex) with ESMTP id AD835C410C7
 for <freebsd-fs@freebsd.org>; Fri, 20 Feb 2015 14:46:41 +0300 (MSK)
Received: from smtp16.mail.yandex.net (localhost [127.0.0.1])
 by smtp16.mail.yandex.net (Yandex) with ESMTP id 5746E6A00EB
 for <freebsd-fs@freebsd.org>; Fri, 20 Feb 2015 14:46:41 +0300 (MSK)
Received: from host52-157-155-90.butovo.com (host52-157-155-90.butovo.com
 [90.155.157.52])
 by smtp16.mail.yandex.net (nwsmtp/Yandex) with ESMTPSA id YCVRSyW5Yr-keuuPOVb; 
 Fri, 20 Feb 2015 14:46:40 +0300
 (using TLSv1.2 with cipher AES128-SHA (128/128 bits))
 (Client certificate not present)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex.ru; s=mail;
 t=1424432801; bh=cxSXwpNAt8UZF8vpFgexKOHSgPImU8gUyGDE+6RIIkY=;
 h=Message-ID:Date:From:User-Agent:MIME-Version:To:Subject:
 Content-Type:Content-Transfer-Encoding;
 b=sRG2rRp4aE+WjpP5gDoJz+2MPfbPSAhWhTV1S0W/+bj+hih8eZuevEdplXq40Mk6R
 ofXbTmXzumKcOukZScbXvf8RhXcbQLlkTo/qrvSsz/uVqAdCLHd0sz0Eh7PRpr1XXX
 smWDQukkYi7TqpkwxVntTeim6kyO/EZKmmq+1024=
Authentication-Results: smtp16.mail.yandex.net; dkim=pass header.i=@yandex.ru
Message-ID: <54E71E20.8080303@yandex.ru>
Date: Fri, 20 Feb 2015 14:44:32 +0300
From: "Ilya A. Arkhipov" <rum1cro@yandex.ru>
User-Agent: Mozilla/5.0 (X11; FreeBSD amd64;
 rv:31.0) Gecko/20100101 Thunderbird/31.4.0
MIME-Version: 1.0
To: freebsd-fs@freebsd.org
Subject: Disable zfs prefetch by default
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.18-1
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs/>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 20 Feb 2015 11:46:45 -0000

Hi All,

We have zfs prefetch enabled by default with > 4GB, but I didn't seen 
any case for using it, and all tuning guide saying to disable it.

Maybe we disable zfs prefetch by default ? Or could you please provide 
why it needed.

Thanks in advance.

-- 
With Best Regards,
Ilya A. Arkhipov