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From: Ernie Elu <ernie@eis.net.au>
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Date: Tue, 27 May 2003 00:30:42 +1000 (EST)
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Subject: Superblock recovery from backup block 32
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I have an IDE drive running FreeBSD 4.8-RELEASE that had a superblock
corruption on the / partition as a result of a faulty motherboard.

When I do an fsck_ffs -o -b 32 /dev/ad2s2a  it passes all the scans.

However after that fsck_ffs /dev/ad2s2a still fails:

root # fsck_ffs /dev/ad2s2a               
** /dev/ad2s2a
Cannot find file system superblock
/dev/ad2s2a: INCOMPLETE LABEL: type 4.2BSD fsize 0, frag 0, cpg 0, size 13211287

I did a fair bit of reading the archives and I thought that fsck is meant to
replace the faulty superblock automatically when you specify an alternative
with the -b flag, but that is not happening.

Can anyone tell me how to replace the superblock with the copy at block 32
which still seems to be o.k?