From owner-freebsd-hardware@FreeBSD.ORG Fri Jan 9 02:30:21 2009 Return-Path: Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id F0B26106566B; Fri, 9 Jan 2009 02:30:21 +0000 (UTC) (envelope-from fbsd@dannysplace.net) Received: from mail.dannysplace.net (mail.dannysplace.net [213.133.54.210]) by mx1.freebsd.org (Postfix) with ESMTP id A00348FC08; Fri, 9 Jan 2009 02:30:21 +0000 (UTC) (envelope-from fbsd@dannysplace.net) Received: from 203-206-171-212.perm.iinet.net.au ([203.206.171.212] helo=[192.168.10.10]) by mail.dannysplace.net with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.69 (FreeBSD)) (envelope-from ) id 1LL78U-0005u0-IL; Fri, 09 Jan 2009 12:30:20 +1000 Message-ID: <4966B6B1.8020502@dannysplace.net> Date: Fri, 09 Jan 2009 12:30:09 +1000 From: Danny Carroll User-Agent: Thunderbird 2.0.0.19 (Windows/20081209) MIME-Version: 1.0 To: Koen Smits References: <20081031033208.GA21220@icarus.home.lan> <490A8FAD.8060009@dannysplace.net> <491BBF38.9010908@dannysplace.net> <491C5AA7.1030004@samsco.org> <491C9535.3030504@dannysplace.net> <4920E1DD.7000101@dannysplace.net> <20081117070818.GA22231@icarus.home.lan> <496549D9.7010003@dannysplace.net> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Authenticated-User: danny X-Authenticator: plain X-Sender-Verify: SUCCEEDED (sender exists & accepts mail) X-Exim-Version: 4.69 (build at 08-Jul-2008 08:59:40) X-Date: 2009-01-09 12:30:11 X-Connected-IP: 203.206.171.212:2346 X-Message-Linecount: 37 X-Body-Linecount: 22 X-Message-Size: 1938 X-Body-Size: 909 X-Received-Count: 1 X-Recipient-Count: 4 X-Local-Recipient-Count: 4 X-Local-Recipient-Defer-Count: 0 X-Local-Recipient-Fail-Count: 0 X-SA-Exim-Connect-IP: 203.206.171.212 X-SA-Exim-Rcpt-To: kgysmits@gmail.com, koitsu@freebsd.org, freebsd-fs@freebsd.org, freebsd-hardware@freebsd.org X-SA-Exim-Mail-From: fbsd@dannysplace.net X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on ferrari.dannysplace.net X-Spam-Level: X-Spam-Status: No, score=0.2 required=8.0 tests=ALL_TRUSTED,TVD_RCVD_IP autolearn=disabled version=3.2.5 X-SA-Exim-Version: 4.2 X-SA-Exim-Scanned: Yes (on mail.dannysplace.net) Cc: freebsd-fs@freebsd.org, Jeremy Chadwick , freebsd-hardware@freebsd.org Subject: Re: Areca vs. ZFS performance testing. X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: fbsd@dannysplace.net List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Jan 2009 02:30:22 -0000 Koen Smits wrote: > My guess is it probably has to do with the way ZFS does cache flushes: > http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Cache_Flushes > It might be worth it to disable the forced flushing and test again, if > you feel like it. I've just done this and the results are on the same page: http://www.dannysplace.net/quickweb/filesystem%20tests.htm The Excel version is here: http://www.dannysplace.net/quickweb/filesystem%20tests.xls It is a major improvement but I do not know 100% for sure if the disks are protected by the write cache/battery backup when in Passthrough mode. When creating a passthrough disk the "Volume Cache Mode" can be set to "Write Back" or "Write Through". This makes me feel as though the cache is being used and that when the cache is used, so is the BBU. But I cannot be 100% sure. I will send an email to Areca support to ask. -D