From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757850AbYDBOSA (ORCPT ); Wed, 2 Apr 2008 10:18:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756776AbYDBORv (ORCPT ); Wed, 2 Apr 2008 10:17:51 -0400 Received: from mail.syneticon.net ([213.239.212.131]:35387 "EHLO mail2.syneticon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756736AbYDBORu (ORCPT ); Wed, 2 Apr 2008 10:17:50 -0400 Message-ID: <47F39575.40006@wpkg.org> Date: Wed, 02 Apr 2008 16:17:25 +0200 From: Tomasz Chmielewski User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.8) Gecko/20061110 Mandriva/1.5.0.8-1mdv2007.1 (2007.1) Thunderbird/1.5.0.8 Mnenhy/0.7.4.666 MIME-Version: 1.0 To: Artem Bityutskiy Cc: LKML , penberg@cs.helsinki.fi, =?UTF-8?B?SsO2cm4gRW5nZWw=?= , ext-adrian.hunter@nokia.com, jwboyer@gmail.com, w@1wt.eu, "H. Peter Anvin" Subject: Re: UBIFS vs Logfs (was [RFC PATCH] UBIFS - new flash file system) References: <47F1EC20.6050600@wpkg.org> <47F1F644.4060000@yandex.ru> <47F202D9.20405@wpkg.org> <47F2071A.6010406@yandex.ru> In-Reply-To: <47F2071A.6010406@yandex.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Artem Bityutskiy schrieb: > Tomasz Chmielewski wrote: (...) >> Performance is only one factor in the equation. Other factors are: >> cost and reliability. >> >> I speak from experience: flash-based block devices tend to have poor >> wear-levelling (at least Transcend IDE-flash disks). >> To reproduce: >> - format a 2 GB Transcend IDE-flash disk with ext3 >> - write a small file (50-100 kB) >> - update that file ~several hundred thousand times - as you finish, >> IDE-flash disk will have 200-300 badblocks > Yeah, that's bad. But if you have a bad FTL, surely there is not guarantee > a flash FS will help? Isn't it better to use better hardware? > > We did some experiments with MMC cards and we were unable to wear them > out with re-writing the same sectors again and again. This suggests there > _is_ better FTL hardware then that USB stick you was using. > > Anyway, your original mail said Logfs can work with block devices. My > answer - > UBIFS too, but this is very strange to do this IMO. But OK, it might is not > senseless, sorry for the wording. :-) I was thinking why my IDE-flash disk died so soon[1] and how efficient can an internal wear-levelling be in devices which hide its "flashiness" (USB-sticks, IDE-flash disks etc.). Internal wear-levelling mechanism doesn't have a clue about free space on the filesystem - it that case, how can it do any efficient wear-levelling? [1] Well, it didn't die, really. Once I removed the file which was showing I/O errors and did "dd if=/dev/zero of=bigfile", there are no badblocks anymore - probably remapped. -- Tomasz Chmielewski http://wpkg.org