From owner-freebsd-stable@FreeBSD.ORG Mon Aug 29 12:04:23 2005 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A350016A41F for ; Mon, 29 Aug 2005 12:04:23 +0000 (GMT) (envelope-from mkb@incubus.de) Received: from luzifer.incubus.de (incubus.de [80.237.207.83]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2DF7243D46 for ; Mon, 29 Aug 2005 12:04:23 +0000 (GMT) (envelope-from mkb@incubus.de) Received: from drjekyll.mkbuelow.net (p54AA805F.dip0.t-ipconnect.de [84.170.128.95]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by luzifer.incubus.de (Postfix) with ESMTP id 27D2E3578C; Mon, 29 Aug 2005 14:07:14 +0200 (CEST) Received: from drjekyll.mkbuelow.net (mkb@localhost.mkbuelow.net [127.0.0.1]) by drjekyll.mkbuelow.net (8.13.3/8.13.3) with ESMTP id j7TC4GGY001545; Mon, 29 Aug 2005 14:04:22 +0200 (CEST) (envelope-from mkb@drjekyll.mkbuelow.net) Received: (from mkb@localhost) by drjekyll.mkbuelow.net (8.13.3/8.13.3/Submit) id j7TC4Fdj001544; Mon, 29 Aug 2005 14:04:15 +0200 (CEST) (envelope-from mkb) Date: Mon, 29 Aug 2005 14:04:15 +0200 From: Matthias Buelow To: Mark Kirkwood Message-ID: <20050829120415.GA1462@drjekyll.mkbuelow.net> References: <200508282330.09302.dinom@balstonresearch.com> <20050829035729.GH88693@dan.emsphone.com> <200508290225.32394.dinom@balstonresearch.com> <4312B060.4080104@paradise.net.nz> <20050829085140.GA684@drjekyll.mkbuelow.net> <4312ECB6.3000702@paradise.net.nz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4312ECB6.3000702@paradise.net.nz> User-Agent: Mutt/1.4.2.1i Cc: freebsd-stable@freebsd.org, "C. Michailidis" Subject: Re: Sysinstall automatic filesystem size generation. X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 29 Aug 2005 12:04:23 -0000 Mark Kirkwood wrote: >>>FreeBSD's filesystems are very robust should you lose power. >>This sentence is completely bogus (or at best: wishful thinking) >>and should be deleted. >It's probably correct if you have hw.ata.wc=0 (and are using IDE drives >obviously). I'd like to stress the "probably". I've already seen unrepairable filesystem corruption with softupdates enabled in the past with "good" scsi disks at power loss. Furthermore, disabling the write-back cache in a typical consumer (read: typical PC workstation) environment today, with large IDE/SATA drives, is unrealistic because of the severe performance degradation, and might even be counter-indicated due to the increased wear&tear on the disk, which might significantly reduce the disk's lifetime. Softupdates works only in an idealized environment that doesn't match against reality. In addition, with softupdates there seems to be a much higher probability of losing files, as I have observed.. that is, getting them zero-truncated, or even deleted (which shouldn't happen in that scenario, I'm sure I've seen the results of a bug), than without. Do I still use softupdates? Yes, because of the performance benefit, but I don't treat it as much different than completely asynchronous operation, with the only difference that it's a slightly more resilient in case of a kernel crash (vs. a power outage) and I make frequent backups. mkb.