Date: Sat, 22 Aug 2009 02:28:22 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: current@freebsd.org Subject: Re: Cannot mount / from UFS labels Message-ID: <20090822002822.GA2613@garage.freebsd.pl> In-Reply-To: <20090821131723.GA91417@acme.spoerlein.net> References: <20090821131723.GA91417@acme.spoerlein.net>
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[-- Attachment #1 --] On Fri, Aug 21, 2009 at 03:17:23PM +0200, Ulrich Spörlein wrote: > Hello, > > I'm not sure this ever worked for 7.x but now I need to have the same > root fs device on two machines: labels to the rescue! As I don't want to > use the GEOM labels, but UFS labels, this is what I did: > > # tunefs -L root / (in single user) > then updated /etc/fstab and rebooted The problem is this: tunefs will write volume name into file system's superblock on the disk. Then you remount read-write and UFS will overwrite superblock with in-memory copy it picked up on first read-only mount (no volume name in there). So there will be no volume name in the superblock anymore. You can confirm that with: # tunefs -L root /dev/ad0s1a # dumpfs /dev/ad0s1a | grep volname There should be volume name here. # mount -uw / # dumpfs /dev/ad0s1a | grep volname No volume name here. You cannot remount it read-only again and use tunefs again, because this is a bit of a hack how it works now. Only first read-only mount opens GEOM provider (eg. /dev/ad0s1a) for reading, but without exclusive bit. Once you remount it the exclusive bit will be there and you will no longer be able to use tunefs on this file system. You can confirm that with: # gpart list | grep -A3 'Name: ad0s1a' Take a look at the 'e' (exclusive) count. So what you have to do instead is to boot into single-user mode, put volume name using tunefs and reboot without remounting the file system. After the reboot, boot it again into single-user mode, remount it read-write and edit /etc/fstab. Alternatively for the second single-user mode boot you can change root provider from loader prompt with this command: OK set vfs.root.mountfrom="ufs:/dev/ufs/root" OK boot And once you boot, edit /etc/fstab. -- Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQFKjzumForvXbEpPzQRAsW6AKC99En9Qeu+V8AgllMIPWLw98eYCQCgo8u5 NIyt9aumzPMuMb+r4hMENaI= =rMHR -----END PGP SIGNATURE-----
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