From: Chris Worley Subject: Re: Plans to evaluate the reliability and integrity of ext4 against power failures. Date: Wed, 1 Jul 2009 12:07:49 -0600 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, fs-team@google.com To: Shaozhi Ye Return-path: Received: from mail-pz0-f188.google.com ([209.85.222.188]:63207 "EHLO mail-pz0-f188.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754340AbZGASHr (ORCPT ); Wed, 1 Jul 2009 14:07:47 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jun 30, 2009 at 5:27 PM, Shaozhi Ye wrote: > Hi there, > > We are planing to evaluate the reliability and integrity of ext4 > against power failures and will post the results when its done. > Please find attached design document and let me know if you have any > suggestions for features to test or existing benchmark tools which > serve our purpose. This looks like a very valuable project. I do lack understanding of how certain problems that very much need to be tested will be tested. >From your pdf: "Data loss: The client thinks the server has A while the server does not." I've been wondering how you test to assure that data committed to the disk is really committed? Ext4 receives the callback saying the data is committed; you need to somehow log what it thinks has been committed and then cut power without any time passing from the moment the callback was invoked, then check the disk upon reboot to assure the data made it by comparing it with the log. I just don't see a method to test this, but it is so critically important. Chris > > Thank you! > > -- > Shaozhi Ye > Software Engineer Intern from UC Davis > Cluster Management Team > http://who/yeshao >