From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966192AbXDGRkI (ORCPT ); Sat, 7 Apr 2007 13:40:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966188AbXDGRkH (ORCPT ); Sat, 7 Apr 2007 13:40:07 -0400 Received: from h80ad275a.async.vt.edu ([128.173.39.90]:42176 "EHLO h80ad275a.async.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933605AbXDGRkF (ORCPT ); Sat, 7 Apr 2007 13:40:05 -0400 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.2 To: johnrobertbanks@fastmail.fm Cc: Jan Harkes , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: Reiser4. BEST FILESYSTEM EVER. In-Reply-To: Your message of "Fri, 06 Apr 2007 19:47:36 PDT." <1175914056.9653.1183426876@webmail.messagingengine.com> From: Valdis.Kletnieks@vt.edu References: <46157B5B.5000602@gmail.com> <1175817921.18400.1183285196@webmail.messagingengine.com> <461592FB.5060507@zytor.com> <1175819681.20754.1183287946@webmail.messagingengine.com> <461596DE.2020802@zytor.com> <1175823288.25662.1183293506@webmail.messagingengine.com> <4615C780.5040407@zytor.com> <1175833931.8916.1183307802@webmail.messagingengine.com> <20070406152119.GC4228@delft.aura.cs.cmu.edu> <1175914056.9653.1183426876@webmail.messagingengine.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1175967598_4736P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Sat, 07 Apr 2007 13:39:58 -0400 Message-ID: <14921.1175967598@turing-police.cc.vt.edu> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --==_Exmh_1175967598_4736P Content-Type: text/plain; charset=us-ascii On Fri, 06 Apr 2007 19:47:36 PDT, johnrobertbanks@fastmail.fm said: > On Fri, 6 Apr 2007 11:21:19 -0400, "Jan Harkes" > > With compression there is a pretty high probability that one corrupted > > byte or disk block will result in loss of a considerably larger amount > > of data. > > Bad blocks are NOT dealt with by the filesystem,... so your comment is > irrelevant, or just plain wrong. > > If your filesystem is writing to bad blocks, then throw away your > operating system. You know... occasionally, blocks go bad *after* you write to them. If you have an uncompressed filesystem, it's often possible to recover most of the file , and just have a few 512-byte blocks of zeros, simply by doing something like 'dd if=bad.file of=bad.file bs=512 conv=noerror' or careful applications of 'skip=N'. If it's compressed, you usually can't recover the rest of a compression group if a previous block is lost. (And for those who talk about backups - yes, taking backups is good. However, it's the rare laptop or desktop machine that can afford the luxury of RAID disks, and backups usually happen once a night, if that often. This means that if you've been working hard on something important all day, and the disk blows chunks at 4:30PM, you *will* be suddenly very concerned over exactly how much you can recover off the failing drive.... And yes, I'd *love* to have all my users connected to nice SAN systems that do snapshotting and remote replication to DR sites and all that - but have you ever *priced* a petabyte of SAN storage, the NAS gateways to serve it to users, and upgrading several tens of thousands of network ports to Gig-E? Hint - US$1M would get us through a pilot, and probably $5M and up to *start* deployment. Anybody wanna buy us an EMC DMX-3? :) http://www.emc.com/products/systems/symmetrix/DMX_series/DMX3.jsp --==_Exmh_1175967598_4736P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFGF9ducC3lWbTT17ARAgoTAJ9Hg1wWgLQ47Uuk0kCh+RIiv+1/VQCg2nHw w1Iycl0MQx6w3XtS1n0rMHA= =aO8Q -----END PGP SIGNATURE----- --==_Exmh_1175967598_4736P--