From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753923AbXLAMNT (ORCPT ); Sat, 1 Dec 2007 07:13:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752564AbXLAMNB (ORCPT ); Sat, 1 Dec 2007 07:13:01 -0500 Received: from lucidpixels.com ([75.144.35.66]:50275 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752702AbXLAMNA (ORCPT ); Sat, 1 Dec 2007 07:13:00 -0500 Date: Sat, 1 Dec 2007 07:12:59 -0500 (EST) From: Justin Piszcz X-X-Sender: jpiszcz@p34.internal.lan To: Jan Engelhardt cc: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, apiszcz@solarrain.com Subject: Re: Kernel 2.6.23.9 + mdadm 2.6.2-2 + Auto rebuild RAID1? In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 1 Dec 2007, Jan Engelhardt wrote: > > On Dec 1 2007 06:19, Justin Piszcz wrote: > >> RAID1, 0.90.03 superblocks (in order to be compatible with LILO, if >> you use 1.x superblocks with LILO you can't boot) > > Says who? (Don't use LILO ;-) I like LILO :) > >> , and then: >> >> /dev/sda1+sdb1 <-> /dev/md0 <-> swap >> /dev/sda2+sdb2 <-> /dev/md1 <-> /boot (ext3) >> /dev/sda3+sdb3 <-> /dev/md2 <-> / (xfs) >> >> All works fine, no issues... >> >> Quick question though, I turned off the machine, disconnected /dev/sda >> from the machine, boot from /dev/sdb, no problems, shows as degraded >> RAID1. Turn the machine off. Re-attach the first drive. When I boot >> my first partition either re-synced by itself or it was not degraded, >> was is this? > > If md0 was not touched (written to) after you disconnected sda, it also > should not be in a degraded state. > >> So two questions: >> >> 1) If it rebuilt by itself, how come it only rebuilt /dev/md0? > > So md1/md2 was NOT rebuilt? Correct. > >> 2) If it did not rebuild, is it because the kernel knows it does not >> need to re-calculate parity etc for swap? > > Kernel does not know what's inside an md usually. And it should not > try to be smart. Ok. > >> I had to: >> >> mdadm /dev/md1 -a /dev/sda2 >> and >> mdadm /dev/md2 -a /dev/sda3 >> >> To rebuild the /boot and /, which worked fine, I am just curious >> though why it works like this, I figured it would be all or nothing. > > Devices are not automatically readded. Who knows, maybe you inserted a > different disk into sda which you don't want to be overwritten. Makes sense, I just wanted to confirm that it was normal.. > >> More info: >> >> Not using ANY initramfs/initrd images, everything is compiled into 1 >> kernel image (makes things MUCH simpler and the expected device layout >> etc is always the same, unlike initrd/etc). >> > My expected device layout is also always the same, _with_ initrd. Why? > Simply because mdadm.conf is copied to the initrd, and mdadm will > use your defined order. > That is another way as well, people seem to be divided.