Date: Thu, 23 Oct 2008 10:42:26 -0500 From: Greg Larkin <glarkin@FreeBSD.org> To: Chris Pratt <eagletree@hughes.net> Cc: FreeBSD-Questions Questions <freebsd-questions@freebsd.org> Subject: Re: Boot device question Message-ID: <49009B62.30507@FreeBSD.org> In-Reply-To: <E4DE4EFF-905B-46B1-82D8-B2F2C1AB764D@hughes.net> References: <E4DE4EFF-905B-46B1-82D8-B2F2C1AB764D@hughes.net>
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-----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-----
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