From owner-cvs-all@FreeBSD.ORG Thu Jul 22 17:03:25 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 053A916A4CE; Thu, 22 Jul 2004 17:03:25 +0000 (GMT) Received: from av8-2-sn3.vrr.skanova.net (av8-2-sn3.vrr.skanova.net [81.228.9.184]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3ED4543D45; Thu, 22 Jul 2004 17:03:24 +0000 (GMT) (envelope-from manlix@demonized.net) Received: by av8-2-sn3.vrr.skanova.net (Postfix, from userid 502) id EA5B938711; Thu, 22 Jul 2004 19:03:22 +0200 (CEST) Received: from smtp3-1-sn3.vrr.skanova.net (smtp3-1-sn3.vrr.skanova.net [81.228.9.101]) by av8-2-sn3.vrr.skanova.net (Postfix) with ESMTP id D9CB137E9C; Thu, 22 Jul 2004 19:03:22 +0200 (CEST) Received: from fisk.demonized.net (h144n2fls33o834.telia.com [213.66.186.144]) by smtp3-1-sn3.vrr.skanova.net (Postfix) with ESMTP id DB63E37E49; Thu, 22 Jul 2004 19:03:17 +0200 (CEST) Received: from beard.demonized.net (beard.demonized.net [192.168.0.2]) by fisk.demonized.net (Postfix) with SMTP id 4B5FD60E7; Thu, 22 Jul 2004 19:03:24 +0200 (CEST) Date: Thu, 22 Jul 2004 19:03:18 +0200 From: Johan Pettersson To: Scott Long Message-Id: <20040722190318.5fe349d3.manlix@demonized.net> In-Reply-To: <40FFC4CD.4080706@samsco.org> References: <200407212045.i6LKjHvX090599@palm.tree.com> <40FEE569.2010209@elischer.org> <40FEE6CA.3090005@samsco.org> <20040722092441.GH3001@cirb503493.alcatel.com.au> <40FFC4CD.4080706@samsco.org> X-Mailer: Sylpheed version 0.9.12 (GTK+ 1.2.10; i386-portbld-freebsd5.2) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit cc: PeterJeremy@optushome.com.au cc: src-committers@freebsd.org cc: cvs-all@freebsd.org cc: cvs-src@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 17:03:25 -0000 On Thu, 22 Jul 2004 07:44:45 -0600 Scott Long wrote: > 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? > > > > That's a very good question. A group at RPI has been working on it > for some time, but I'm not sure how close they are to having it done. > If you look in the commercial world, Apple, Sun, and Wasabi/NetBSD > have all done it successfully (Wasabi's isn't open source, btw). My > guess is that it would take about 4-5 months to get it going, and then > at least 8-12 months to ensure that there are no bugs and to tune > performance. Certainly not impossible, but not something that would be > production quality on short notice. I think that you would also have > to make it othogonal to softupdates. > > The gain that you get is that your filesystem recovery time drops > tremendously. You also have a much better chance of all of the > metadata being on the disk and recoverable. Furthermore, it opens the > door for data+metadata journalling for even more protection (at a > large cost to speed and/or buffer-cache pressure, of course). > > Scott Isn't there ongoing work to port XFS to FreeBSD?