Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932781AbXA1ToW (ORCPT ); Sun, 28 Jan 2007 14:44:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932783AbXA1ToW (ORCPT ); Sun, 28 Jan 2007 14:44:22 -0500 Received: from hobbit.corpit.ru ([81.13.94.6]:22114 "EHLO hobbit.corpit.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932781AbXA1ToV (ORCPT ); Sun, 28 Jan 2007 14:44:21 -0500 Message-ID: <45BCFD10.4070302@tls.msk.ru> Date: Sun, 28 Jan 2007 22:44:16 +0300 From: Michael Tokarev Organization: Telecom Service, JSC User-Agent: Icedove 1.5.0.9 (X11/20061220) MIME-Version: 1.0 To: Jan Engelhardt CC: Marc Perkel , linux-kernel@vger.kernel.org Subject: Re: Raid 10 question/problem [ot] References: <593246.19408.qm@web52505.mail.yahoo.com> <45BC6740.1000606@tls.msk.ru> In-Reply-To: X-Enigmail-Version: 0.94.1.0 OpenPGP: id=4F9CF57E Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2093 Lines: 58 Jan Engelhardt wrote: > On Jan 28 2007 12:05, Michael Tokarev wrote: [] >> Mdadm creates those nodes automa[tg]ically - man mdadm, search for --auto. > > Note that `mdadm -As` _is_ run on FC6 boot. See above -- man mdadm, search for --auto. -A = --assemble, -s = --scan. >> In order for an md array to be started up on boot, it has to be specified >> in /etc/mdadm.conf. With proper DEVICE line in there. That's all. > > That's how it is, and it does not work. Sure. Because of this missing --auto flag. > openSUSE 10.2: > no mdadm.conf _at all_, /etc/init.d/boot.d/boot.md is chkconfig'ed _out_, > _no_ md kernel module is loaded, and I still have all the /dev/md nodes. And no udev. Or, alternatively, *all* md devices are created by some other script or somesuch. There's No Magic (tm). [] > # mdadm -C /dev/md1 -e 1.0 -l 1 -n 2 /dev/sdb2 /dev/sdc2 > mdadm: error opening /dev/md1: No such file or directory > > Showstopper. Nonsense. See above again, man mdadm, search for --auto. [] > You see, I have all the reason to be confused. Yeah, this is quite... confusing. It's all due to the way how mdadm iteracts with the kernel and how udev works - all together. The thing is - in order to assemble an array, proper device node has to be in place. But udev wont create it until array is assembled. Chicken&eggs problem. Exactly due to this, the node(s) can be created with mdadm (with --auto option, whicih can be specified in mdadm.conf too), AND/OR with some startup script before invoking mdadm, AND/OR when the system isn't broken by udevd (with ol'good static /dev). >> But in any case, this has exactly nothing to do with kernel. >> It's 100% userspace issues, I'd say distribution-specific issues. ..And each distribution uses its own kludge/workaround/solution for this stuff - which you demonstrated... ;) /mjt - 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/