From owner-freebsd-stable@FreeBSD.ORG Mon Aug 29 21:15:27 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 860A716A41F for ; Mon, 29 Aug 2005 21:15:27 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1779B43D48 for ; Mon, 29 Aug 2005 21:15:27 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id 66C735F54; Mon, 29 Aug 2005 17:15:26 -0400 (EDT) Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 16605-06; Mon, 29 Aug 2005 17:15:22 -0400 (EDT) Received: from [192.168.1.3] (pool-68-161-79-217.ny325.east.verizon.net [68.161.79.217]) by pi.codefab.com (Postfix) with ESMTP id 099785C74; Mon, 29 Aug 2005 17:15:21 -0400 (EDT) Message-ID: <43137AFB.9060304@mac.com> Date: Mon, 29 Aug 2005 17:15:39 -0400 From: Chuck Swiger Organization: The Courts of Chaos User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.11) Gecko/20050801 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Matthias Buelow References: <20050829120415.GA1462@drjekyll.mkbuelow.net> <200508291836.j7TIaVEk013147@gw.catspoiler.org> <20050829185933.GB1462@drjekyll.mkbuelow.net> <431362ED.9030800@mac.com> <20050829204714.GC1462@drjekyll.mkbuelow.net> In-Reply-To: <20050829204714.GC1462@drjekyll.mkbuelow.net> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: amavisd-new at codefab.com Cc: freebsd-stable@freebsd.org 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 21:15:27 -0000 Matthias Buelow wrote: > Chuck Swiger wrote: >>PS: Haven't we had this conversation before? > > Yes, indeed, and I don't want to reopen that issue since that would > lead to no new insights (and since I don't have the time atm. to > contribute anything I couldn't provide any stuff myself). Yet you seem willing to spend time discussing the matter...? > I was just refuting the claim of "very robust" filesystem when power goes > out in the context of 200GB consumer-grade hardware that this thread > was talking about. Most of the time, a FreeBSD system will come back up without losing data older than about thirty seconds, and that is tunable. Have you even tried to change the syncer sysctls I mentioned? > I think until a satisfactory solution can be > found (by making softupdates and/or a journalled filesystem as > reliable as possible through mechanisms like write-request barriers > and appropriate flushing at these) users who're running FreeBSD on > end-consumer hardware (desktop PC as workstation or personal server) > should be warned that softupdates does NOT work as described on > their hardware and that the filesystem can easily be corrupted when > the power goes out, no matter if softupdates is enabled or not. Great. I think "man ata" already says exactly this: hw.ata.wc set to 1 to enable Write Caching, 0 to disable (default is enabled). WARNING: can cause data loss on power failures. If your hard drive no longer works correctly when write-caching is disabled, it's defective. Nothing FreeBSD or any other system can do is going to change that. > One often sees the "softupdates" argument being fielded by FreeBSD > advocates, typically against Linux users with journalled fs, on web > forums, usenet and other less authoritative (and knowledgable) > places of discussion, and it is often presented as if it were some > kind of magic bullet that makes filesystem corruption impossible. "Often?" Strawman test: can you point out 3 examples by message-id or URL? And if you prefer to run a journalled filesystem under Linux instead of softupdates under FreeBSD, by all means, do whatever makes you happy. > This simply is not so. Very good. -- -Chuck PS: I don't want a thread to end on a negative note. It would be useful if FreeBSD had a more adaptable method for dealing with drive power management and caching; in particular, for laptops it might be nice to cache data for much longer-- perhaps even hours-- if nothing fsync()s, in order to permit the drive to spin down. (This is something both Windows and MacOS X are learning to do pretty well.)