Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751470AbVIVKcc (ORCPT ); Thu, 22 Sep 2005 06:32:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751468AbVIVKcK (ORCPT ); Thu, 22 Sep 2005 06:32:10 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:60329 "EHLO atrey.karlin.mff.cuni.cz") by vger.kernel.org with ESMTP id S1751469AbVIVKcF (ORCPT ); Thu, 22 Sep 2005 06:32:05 -0400 Date: Wed, 21 Sep 2005 21:07:59 +0200 From: Pavel Machek To: J Engel Cc: "Artem B. Bityutskiy" , Peter Menzebach , linux-kernel Subject: Re: data loss on jffs2 filesystem on dataflash Message-ID: <20050921190759.GC467@openzaurus.ucw.cz> References: <432817FF.10307@yandex.ru> <4329251C.7050102@mw-itcon.de> <4329288B.8050909@yandex.ru> <43292AC6.40809@mw-itcon.de> <43292E16.70401@yandex.ru> <43292F91.9010302@mw-itcon.de> <432FE1EF.9000807@yandex.ru> <432FEF55.5090700@mw-itcon.de> <433006D8.4010502@yandex.ru> <20050920133244.GC4634@wohnheim.fh-wedel.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050920133244.GC4634@wohnheim.fh-wedel.de> User-Agent: Mutt/1.3.27i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1375 Lines: 39 Hi! > > I glanced at the manual. Uhh, DataFlash is very specific beast. It > > suppoers page program with built-in erase command... So DataFlash > > effectively may be considered as a block device. Then you may use any FS > > on it providing you have wrote proper driver? Why do you need JFFS2 then > > :-) ? > > Still can't. Block devices have the attribute that writing AAA... to > a block containing BBB... gives you one of three possible results in > case of power failure: > > 1. BBB...BBB all written > 2. AAA...AAA nothing written > 3. AAA...BBB partially written. > > Flash doesn't have 3, but two more cases: > 4. FFF...FFF erased, nothing written > 5. AAA...FFF erased, partially written > > Plus the really obnoxious > 6. FFF...FFF partially erased. Looks fine but some bits may flip > randomly, writes may not stick, etc. > > Now try finding a filesystem that is robust if 4-6 happens. ;) ext2 and anything that does not do journalling? I do not thing behaviour on powerfail is part of block device definition. Pavel -- 64 bytes from 195.113.31.123: icmp_seq=28 ttl=51 time=448769.1 ms - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/