From mboxrd@z Thu Jan 1 00:00:00 1970 From: Edward Shishkin Subject: Re: the " 'official' point of view" expressed by kernelnewbies.org regarding reiser4 inclusion Date: Thu, 03 Aug 2006 19:44:57 +0400 Message-ID: <44D219F9.9080404@namesys.com> 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> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <20060803140344.GC7431@merlin.emma.line.org> List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Matthias Andree Cc: Hans Reiser , 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 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. 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.