From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161327AbWHDREm (ORCPT ); Fri, 4 Aug 2006 13:04:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161328AbWHDREm (ORCPT ); Fri, 4 Aug 2006 13:04:42 -0400 Received: from mail.zelnet.ru ([80.92.97.13]:51584 "EHLO mail.zelnet.ru") by vger.kernel.org with ESMTP id S1161327AbWHDREl (ORCPT ); Fri, 4 Aug 2006 13:04:41 -0400 Message-ID: <44D37E1B.1040109@namesys.com> Date: Fri, 04 Aug 2006 21:04:27 +0400 From: Edward Shishkin Organization: Namesys User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.13) Gecko/20060411 X-Accept-Language: en-us, en, ru MIME-Version: 1.0 To: Hans Reiser CC: Matthias Andree , ric@emc.com, Alan Cox , Adrian Ulrich , "Horst H. von Brand" , bernd-schubert@gmx.de, reiserfs-list@namesys.com, jbglaw@lug-owl.de, clay.barnes@gmail.com, rudy@edsons.demon.nl, ipso@snappymail.ca, lkml@lpbproductions.com, jeff@garzik.org, tytso@mit.edu, linux-kernel@vger.kernel.org Subject: Re: the " 'official' point of view" expressed by kernelnewbies.org regarding reiser4 inclusion References: <200607312314.37863.bernd-schubert@gmx.de> <200608011428.k71ESIuv007094@laptop13.inf.utfsm.cl> <20060801165234.9448cb6f.reiser4@blinkenlights.ch> <1154446189.15540.43.camel@localhost.localdomain> <44CF9BAD.5020003@emc.com> <44CF3DE0.3010501@namesys.com> <20060803140344.GC7431@merlin.emma.line.org> <44D219F9.9080404@namesys.com> <44D231DF.1080804@namesys.com> In-Reply-To: <44D231DF.1080804@namesys.com> X-Enigmail-Version: 0.86.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hans Reiser wrote: > Edward Shishkin wrote: > > >>Matthias Andree wrote: >> >> >>>On Tue, 01 Aug 2006, Hans Reiser wrote: >>> >>> >>> >>>>You will want to try our compression plugin, it has an ecc for every >>>>64k.... >>> >>> >>> >>>What kind of forward error correction would that be, >> >> >> >>Actually we use checksums, not ECC. If checksum is wrong, then run >>fsck - it will remove the whole disk cluster, that represent 64K of >>data. > > > How about we switch to ecc, which would help with bit rot not sector loss? Interesting aspect. Yes, we can implement ECC as a special crypto transform that inflates data. As I mentioned earlier, it is possible via translation of key offsets with scale factor > 1. Of course, it is better then nothing, but anyway meta-data remains ecc-unprotected, and, hence, robustness is not increased.. Edward. > >> >> and how much and >> >> >>>what failure patterns can it correct? URL suffices. >>> >> >>Checksum is checked before unsafe decompression (when trying to >>decompress incorrect data can lead to fatal things). It can be >>broken because of many reasons. The main one is tree corruption >>(for example, when disk cluster became incomplete - ECC can not >>help here). Perhaps such checksumming is also useful for other >>things, I didnt classify the patterns.. >> >>Edward. >> >> > > > >