From owner-cvs-all@FreeBSD.ORG Thu Jul 22 16:32:20 2004 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0E50016A4CE; Thu, 22 Jul 2004 16:32:20 +0000 (GMT) Received: from www.cryptography.com (li-22.members.linode.com [64.5.53.22]) by mx1.FreeBSD.org (Postfix) with ESMTP id C8A6C43D41; Thu, 22 Jul 2004 16:32:19 +0000 (GMT) (envelope-from nate@root.org) Received: from [10.0.0.34] (adsl-63-195-111-154.dsl.snfc21.pacbell.net [63.195.111.154]) by www.cryptography.com (8.12.8/8.12.8) with ESMTP id i6MGWErb012414 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Thu, 22 Jul 2004 09:32:15 -0700 Message-ID: <40FFEB86.2050209@root.org> Date: Thu, 22 Jul 2004 09:29:58 -0700 From: Nate Lawson User-Agent: Mozilla Thunderbird 0.7.1 (Windows/20040626) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Peter Jeremy References: <200407212045.i6LKjHvX090599@palm.tree.com> <40FEE569.2010209@elischer.org> <40FEE6CA.3090005@samsco.org> <20040722092441.GH3001@cirb503493.alcatel.com.au> In-Reply-To: <20040722092441.GH3001@cirb503493.alcatel.com.au> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit cc: cvs-src@freebsd.org cc: Scott Long cc: src-committers@freebsd.org cc: cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/kern kern_shutdown.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Jul 2004 16:32:20 -0000 Peter Jeremy wrote: > On Wed, 2004-Jul-21 15:57:30 -0600, Scott Long wrote: >>Implementing a journalling filesystem would be a much more beneficial >>use of time here. > > You still wind up with unwritten data in RAM, just less of it. > > How much effort would be required to add journalling to UFS or UFS2? > How big a gain does journalling give you over soft-updates? Kirk pointed out something to me the other day which many people don't think about. None of the journaling systems has had its recovery mode fully tested, especially on very large systems (dozen TB). It turns out that memory pressure from per-allocation unit state is a big problem when you are trying to recover a huge volume. Just because it says "journaling" doesn't make it good. -- -Nate