From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757197AbYDAIuP (ORCPT ); Tue, 1 Apr 2008 04:50:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754685AbYDAIuD (ORCPT ); Tue, 1 Apr 2008 04:50:03 -0400 Received: from smtp.nokia.com ([192.100.122.230]:60555 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754506AbYDAIuC (ORCPT ); Tue, 1 Apr 2008 04:50:02 -0400 Message-ID: <47F1F644.4060000@yandex.ru> Date: Tue, 01 Apr 2008 11:45:56 +0300 From: Artem Bityutskiy User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: Tomasz Chmielewski CC: LKML , penberg@cs.helsinki.fi, =?UTF-8?B?SsO2cm4gRW5nZWw=?= , ext-adrian.hunter@nokia.com, jwboyer@gmail.com Subject: Re: UBIFS vs Logfs (was [RFC PATCH] UBIFS - new flash file system) References: <47F1EC20.6050600@wpkg.org> In-Reply-To: <47F1EC20.6050600@wpkg.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-OriginalArrivalTime: 01 Apr 2008 08:49:46.0400 (UTC) FILETIME=[5639BA00:01C893D5] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tomasz Chmielewski wrote: > For me, the motivators to wait for LogFS are mainly the facts that it > can work on traditional block devices, and not only on pure flash: Sorry Thomasz, for me this makes zero sense. There are _much_ better file systems for block devices. UBIFS may work on top of a block device as well (just needs few hacks to make it possible) - it is not a problem at all, it is just _senseless_. JFFS2/UBIFS/LogFS is a separate _class_ of file-systems. The are designed for _flash_, which has completely different work model then block device. They are _native_ flash file systems. Here are more details: http://www.linux-mtd.infradead.org/faq/general.html#L_mtd_vs_hdd The traditional FSes _cannot_ work on top of flash. The solution for this is using FTL, which emulates a block device on top of flash. It _hides_ the real device, and fakes a block device for you. And you can use traditional FSes on top of that fake block device. The whole _point_ of this separate class of FSes is because we believe we may do much _better_ job if we use flash _natively_, instead of using FTL. FTL is the place where you loose performance, reliability, and so on. And you are saying about using a native flash FS on top of a block device like an SD card. This is just not sane: SD card first emulates a block device for you, looses performance at this point, then you again emulate a flash on top of this, and suffer from this again. -- Best Regards, Artem Bityutskiy (Артём Битюцкий)