Date: Tue, 18 Sep 2001 22:36:16 +0100 From: Ian Dowse <iedowse@maths.tcd.ie> To: Aram Khalili <aram@cs.umd.edu> Cc: freebsd-questions@freebsd.org Subject: Re: corrupted superblock/fsck problem Message-ID: <200109182236.aa76960@salmon.maths.tcd.ie> In-Reply-To: Your message of "Tue, 18 Sep 2001 12:22:25 EDT." <Pine.SOL.4.21.0109181213220.10298-100000@toblerone.cs.umd.edu>
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In message <Pine.SOL.4.21.0109181213220.10298-100000@toblerone.cs.umd.edu>, Ara m Khalili writes: > >Yikes, I had assumed it starts at block 0. So what did I clobber? The >boot block? The /home filesystem isn't bootable ... It depends a bit on how the disk is partitioned. If /home was located at the beginning of a slice, then you might have overwritten the disklabel in sector 1 (i.e. the second sector). On a bootable slice, sectors 0 and 2-15 are used by the boot code, and on a "dangerously dedicated" disk, sector 0 also contains the DOS partition table. Another possibility is that you wrote more than 8k to the start of the partition so maybe you did actually clobber the master superblock. >It doesn't include the count of used/free inodes and blocks in the >filesystem (not the bitmap, just the count)? I'm more familiar with ext2, >and I think it does. Yes, there are summary statistics kept in the superblock, but the kernel only ever looks at the master superblock, so it doesn't matter if the backup superblocks are not kept up-to-date. The only thing that reads the backup superblocks is fsck, and it has to know how to recalculate those counts and statistics anyway, since they will be wrong after an unclean shutdown. Ian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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