From owner-freebsd-questions@FreeBSD.ORG Thu Oct 23 15:42:34 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 900E2106566C for ; Thu, 23 Oct 2008 15:42:34 +0000 (UTC) (envelope-from glarkin@FreeBSD.org) Received: from mail1.sourcehosting.net (113901-app1.sourcehosting.net [72.32.213.11]) by mx1.freebsd.org (Postfix) with ESMTP id 717738FC0C for ; Thu, 23 Oct 2008 15:42:34 +0000 (UTC) (envelope-from glarkin@FreeBSD.org) Received: from localhost ([127.0.0.1]) by mail1.sourcehosting.net with esmtp (Exim 4.69 (FreeBSD)) (envelope-from ) id 1Kt2KR-0003fz-Kx; Thu, 23 Oct 2008 11:42:33 -0400 Message-ID: <49009B62.30507@FreeBSD.org> Date: Thu, 23 Oct 2008 10:42:26 -0500 From: Greg Larkin Organization: The FreeBSD Project User-Agent: Thunderbird 2.0.0.16 (X11/20080726) MIME-Version: 1.0 To: Chris Pratt References: In-Reply-To: X-Enigmail-Version: 0.95.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Spam-Score: -4.4 (----) Cc: FreeBSD-Questions Questions Subject: Re: Boot device question X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: glarkin@FreeBSD.org List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Oct 2008 15:42:34 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Chris Pratt wrote: > I have a server with 6 hot-swap SATA slots. It was delivered > with the first slot empty and 5 drives set up as /dev/ad4 through > /dev/ad12. I'd never paid attention to this until I wanted to add > a 6th, now 4 years later. When I popped it in, I realized the > empty bay was not 6 but rather bay 1, and of course it wouldn't > boot. Presumably /dev/ad2 had now come alive for the first time. > I popped out the disk, rebooted and after it was up, I plugged it > back in (hot) and ran sysinstall. It didn't see the disk so I couldn't > fdisk it. No device files existed for it. > > I was thinking a right approach would be to change fstab to > reference ad2 for all the system disk file systems, shutdown, > move that drive to the first bay and plug the new drive into the > 2nd bay. This seemed like more of a permanent solution. > If those /dev/ad* files are created at boot dynamically, > this should work. I've found docs that imply that they are > dynamically discovered and created from FreeBSD 5 forward > (auto-discovery?). Are they or do I need to create them prior to > start up. > > The thing is, there is no easy recovery from failure here since I > have no console monitor to let me see what's going on or to fix > fstab if it fails (counter-intuitively, the only place I can access > the console is from remote locations ;-)), so I just want to know > if I'm thinking straight? The plan is: > > 1. Change /etc/fstab entries for ad4 filesystems to ad2 > 2. Shutdown > 3. Put the system disk in Bay 1 > 4. Power up > > Should it boot? Hi Chris, I don't know the answer to that question, but I do know that you can wire physical devices to specific devices files in /dev. I use the /boot/device.hints file to do that. Check this page for more information: http://threads.seas.gwu.edu/cgi-bin/man2web?program=scbus§ion=4 Halfway down the page, you'll see directives like: hint.da.0.at="scbus0" hint.da.0.target="0" hint.da.0.unit="0" I believe you can do something similar with your ad devices, and force the new drive to a different /dev/ad? device file that doesn't cause a boot problem. Hope that helps, Greg -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkkAm2EACgkQ0sRouByUApARlQCcDmUTbVBqui+nNSpcCdDTavIk FywAnj+wR4wtB8vLsYL0BiEfdiRLPnq6 =Y3ZT -----END PGP SIGNATURE-----