From owner-cvs-all@FreeBSD.ORG Thu Jul 22 17:09:07 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 DEFFC16A4E7; Thu, 22 Jul 2004 17:09:07 +0000 (GMT) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3D80843D46; Thu, 22 Jul 2004 17:09:05 +0000 (GMT) (envelope-from scottl@freebsd.org) Received: from [192.168.0.12] (g4.samsco.home [192.168.0.12]) (authenticated bits=0) by pooker.samsco.org (8.12.11/8.12.10) with ESMTP id i6MHFLSj067831; Thu, 22 Jul 2004 11:15:22 -0600 (MDT) (envelope-from scottl@freebsd.org) Message-ID: <40FFF46A.2080703@freebsd.org> Date: Thu, 22 Jul 2004 11:07:54 -0600 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7) Gecko/20040514 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Nate Lawson References: <200407212045.i6LKjHvX090599@palm.tree.com> <40FEE569.2010209@elischer.org> <40FEE6CA.3090005@samsco.org> <20040722092441.GH3001@cirb503493.alcatel.com.au> <40FFEB86.2050209@root.org> In-Reply-To: <40FFEB86.2050209@root.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=0.0 required=3.8 tests=none autolearn=no version=2.63 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on pooker.samsco.org cc: Peter Jeremy cc: Scott Long 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 17:09:08 -0000 Nate Lawson 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? > > > 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. > You are very correct that there are issues like this, and that's why I said that it would take a while to chase out the bugs and make it production quality. However, given the enterprise nature of Sun, I'd say it's a bit of a stretch to think that they haven't tested their f/s on multi-terabyte arrays. Even Apple advertises multi-terabyte storage with their XServe, so I'd be surprised if they hadn't done at least some testing there. Scott