Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752648AbWKBXM0 (ORCPT ); Thu, 2 Nov 2006 18:12:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751010AbWKBXM0 (ORCPT ); Thu, 2 Nov 2006 18:12:26 -0500 Received: from sp604005mt.neufgp.fr ([84.96.92.11]:46728 "EHLO smtp.Neuf.fr") by vger.kernel.org with ESMTP id S1750698AbWKBXMZ (ORCPT ); Thu, 2 Nov 2006 18:12:25 -0500 Date: Fri, 03 Nov 2006 00:10:20 +0100 From: Eric Dumazet Subject: Re: New filesystem for Linux In-reply-to: To: Grzegorz Kulewski Cc: Mikulas Patocka , linux-kernel@vger.kernel.org Message-id: <454A7ADC.4030203@cosmosbay.com> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 8BIT References: User-Agent: Thunderbird 1.5.0.7 (Windows/20060909) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1762 Lines: 44 Grzegorz Kulewski a ?crit : > Hi, > > On Thu, 2 Nov 2006, Mikulas Patocka wrote: >> As my PhD thesis, I am designing and writing a filesystem, and it's >> now in a state that it can be released. You can download it from >> http://artax.karlin.mff.cuni.cz/~mikulas/spadfs/ > > "Disk that can atomically write one sector (512 bytes) so that the sector > contains either old or new content in case of crash." > > Well, maybe I am completly wrong but as far as I understand no disk > currently will provide such requirement. Disks can have (after halted > write): > - old data, > - new data, > - nothing (unreadable sector - result of not full write and disk > internal checksum failute for that sector, happens especially often if > you have frequent power outages). > I believe some vendors have such devices. Mikulas called them 'disk', but it's in fact a (disk(s), controler, ram, battery) Some controlers are even able to write into flash memory the un-written data when/if the battery/power is about to fail. When power goes up, controler can finaly do the writes on disks. > And possibly some broken drives may also return you something that they > think is good data but really is not (shouldn't happen since both disks > and cables should be protected by checksums, but hey... you can never be > absolutely sure especially on very big storages). > > So... isn't this making your filesystem a little flawed in design? Well... even RAM can fail :) In this case isnt linux flawed in design ? - 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/