From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751770AbWBWTqq (ORCPT ); Thu, 23 Feb 2006 14:46:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751769AbWBWTqq (ORCPT ); Thu, 23 Feb 2006 14:46:46 -0500 Received: from watts.utsl.gen.nz ([202.78.240.73]:45989 "EHLO mail.utsl.gen.nz") by vger.kernel.org with ESMTP id S1751767AbWBWTqp (ORCPT ); Thu, 23 Feb 2006 14:46:45 -0500 Message-ID: <43FE1110.1030707@vilain.net> Date: Fri, 24 Feb 2006 08:46:24 +1300 From: Sam Vilain User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051013) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Theodore Ts'o" Cc: Xin Zhao , Arjan van de Ven , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: question about possibility of data loss in Ext2/3 file system References: <4ae3c140602221356x15015171h5aa4a3d7bb6034e0@mail.gmail.com> <1140645651.2979.79.camel@laptopd505.fenrus.org> <4ae3c140602221434v6ec583a7yf04df5fa7a4948fc@mail.gmail.com> <20060223045836.GC9645@thunk.org> In-Reply-To: <20060223045836.GC9645@thunk.org> X-Enigmail-Version: 0.92.1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Theodore Ts'o wrote: >>Also, the scheme you mentioned is just for new file creation. What >>will happen if I want to update an existing file? Say, I open file A, >>seek to offset 5000, write 4096 bytes, and then close. Do you know how >>ext2/3 handle this situation? > If you have a power failure right after the close, the data could be > lost. This is true for pretty much all Unix filesystems, for > performance reasons. If you care about the data hitting disk, the > application must use fsync(). I always liked Sun's approach to this in Online Disk Suite - journal at the block device level rather than the FS / application level. Something I haven't seen from the Linux md-utils or DM. Sam.