Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 27 Jul 2001 13:41:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 27 Jul 2001 13:41:49 -0400 Received: from ACAP-DEV.NAS.CMU.EDU ([128.2.6.63]:49670 "EHLO acap-dev.nas.cmu.edu") by vger.kernel.org with ESMTP id ; Fri, 27 Jul 2001 13:41:38 -0400 Date: Fri, 27 Jul 2001 13:41:40 -0400 Message-Id: <200107271741.f6RHfe8U010593@acap-dev.nas.cmu.edu> From: Lawrence Greenfield X-Mailer: BatIMail version 3.2 To: Alan Cox Cc: linux-kernel@vger.kernel.org In-Reply-To: Subject: Re: ext3-2.4-0.9.4 In-Reply-To: Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Original-Recipient: rfc822;linux-kernel-outgoing Date: Fri, 27 Jul 2001 17:50:29 +0100 (BST) Cc: linux-kernel@vger.kernel.org From: Alan Cox [...] > Thus why all reasonably paranoid MTAs and other mail programs say "use > chattr +S on ext2"---we need ordered metadata writes. And then your IDE disk gets you anyway. Also if you write metadata first then you risk delivering email to the wrong person instead. These are tangential issues. Not everybody uses IDE disks. I'm not asking for things that are impossible. Just because sometimes the hardware screws you isn't a good reason for not trying to do the right thing. The application can avoid the wrong file problem by zeroing out data before releasing it to the OS to reallocate. > You want to help performance? Give us an fsync() that works on > multiple file descriptors at once, or an async fsync() call. Don't > make us fight the OS on getting data to disk. And what pray does an asynchronous fsync do. It seems to be a nop to me. An async fsync allows me to issue multiple fsyncs and then wait for all of them to complete, hopefully in the same framework that I would do async I/O (but that's an argument for another day). Doing reliabile transactions on disk is a hard problem. That is why oracle and friends have spent many man years of research on this kind of problem. Current unix mailers do the smoke mirrors and prayer bit to reduce the probability a little that is all, regardless of fs and os. Isn't the point of the operating system to try to make it as easy as possible to do these things correctly? Otherwise you force anyone who wants to write a reliable application (be it e-mail or not) to go to Oracle and one wonders why fsync() is even implemented. Larry - 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/