From: Ron Johnson Subject: Re: raid is dangerous but that's secret (was Re: [patch] ext2/3: document conditions when reliable operation is possible) Date: Mon, 31 Aug 2009 18:19:25 -0500 Message-ID: <4A9C5A7D.8000302@cox.net> References: <4A947682.2010204@redhat.com> <4A967175.5070700@redhat.com> <20090827221319.GA1601@ucw.cz> <4A9733C1.2070904@redhat.com> <20090828064449.GA27528@elf.ucw.cz> <20090828120854.GA8153@mit.edu> <20090830075135.GA1874@ucw.cz> <20090830152023.GB23828@mit.edu> <4807377b0908311049id9a2167r937bc8447c2b3546@mail.gmail.com> <20090831180746.GA32110@piper.oerlikon.madduck.net> <4807377b0908311526r3b42f581j27b9c26166b7ac96@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Theodore Tso , Ric Wheeler , Linux-Ext4 To: Jesse Brandeburg Return-path: Received: from eastrmmtao102.cox.net ([68.230.240.8]:49508 "EHLO eastrmmtao102.cox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751645AbZHaXTY (ORCPT ); Mon, 31 Aug 2009 19:19:24 -0400 In-Reply-To: <4807377b0908311526r3b42f581j27b9c26166b7ac96@mail.gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2009-08-31 17:26, Jesse Brandeburg wrote: > On Mon, Aug 31, 2009 at 11:07 AM, martin f krafft wrote: >> also sprach Jesse Brandeburg [2009.08.31.1949 +0200]: >>> In the case of a degraded array, could the kernel be more >>> proactive (or maybe even mdadm) and have the filesystem remount >>> itself withOUT journalling enabled? This seems on the surface to >>> be possible, but I don't know the internal particulars that might >>> prevent/allow it. >> Why would I want to disable the filesystem journal in that case? > > I misspoke w.r.t journalling, the idea I was trying to get across was > to remount with -o sync while running on a degraded array, but given > some of the other comments in this thread I'm not even sure that would > help. the idea was to make writes as safe as possible (at the cost of > speed) when running on a degraded array, and to have the transition be > as hands-free as possible, just have the kernel (or mdadm) by default > remount. Much better, I'd think, to "just" have it scream out DANGER!! WILL ROBINSON!! DANGER!! to syslog and to an email hook. -- Brawndo's got what plants crave. It's got electrolytes!