From: Eric Sandeen Subject: Re: breaking ext4 to test recovery Date: Thu, 31 Mar 2011 17:44:16 -0500 Message-ID: <4D9503C0.8080804@redhat.com> References: <25B374CC0D9DFB4698BB331F82CD0CF20D61B8@wdscexbe08.sc.wdc.com> <4D91E39A.3000800@redhat.com> <6617927D-7C9C-4D02-97FD-C9CC75609448@dilger.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Daniel Taylor , linux-ext4@vger.kernel.org To: Andreas Dilger Return-path: Received: from mx1.redhat.com ([209.132.183.28]:7552 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751664Ab1CaWoV (ORCPT ); Thu, 31 Mar 2011 18:44:21 -0400 In-Reply-To: <6617927D-7C9C-4D02-97FD-C9CC75609448@dilger.ca> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 3/31/11 5:21 PM, Andreas Dilger wrote: > We have a kernel patch "dev_read_only" that we use with Lustre to > disable writes to the block device while the device is in use. This > allows simulating crashes at arbitrary points in the code or test > scripts. It was based on Andrew Morton's test harness that he used > for ext3 recovery testing back when it was being ported to the 2.4 > kernel. > > http://git.whamcloud.com/?p=fs/lustre-release.git;a=blob_plain;f=lustre/kernel_patches/patches/dev_read_only-2.6.32-rhel6.patch;hb=HEAD > > The best part of this patch is that it works with any block device, > can simulate power failure w/o any need for automated power control, > and once the block device is unused (all buffers and references > dropped) it can be re-activated safely. It won't simulate a lost write cache though, will it? -Eric