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Folks,
The following script helped me recover my ext2 filesystems
after a misadventure with partitioning... Here's what the
output looks like on a normal partition with an ext2 fs.
# ./find_superblock_offsets.pl
bytes sectors blocks
1024 2 1
8389632 16386 8193
16778240 32770 16385
25166848 49154 24577
33555456 65538 32769
I used this to determine the offsets for my partition table.
Once the partition table had been restored, the filesystems
reappeared, none the worse for their journey in the void.
For all you people who use "/sbin/fdisk -l" to take a copy of
your partition table, I recommend you also note the output of
"/sbin/fdisk -lu" to record the sectors offsets as well, just
in case any of your partitions aren't on cylinder boundaries.
Yours sincerely,
- -- Mark John Suter | I know that you believe you understand
suter at humbug.org.au | what you think I said, but I am not sure
Use GPG encryption | you realise that what you heard is not
Ph: +61 4 1126 2316 | what I meant. anonymous
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#!/usr/bin/perl -w
use strict;
my $device = "/dev/hda1";
open OD, "/usr/bin/od --address-radix=d --format=x2 --width=2 $device |" or
die "Unable to dump $device: $!\n";
printf("%8s %8s %8s\n", "bytes", "sectors", "blocks");
while (<OD>) {
next unless /ef53/;
# ef53 is the MAGIC for ext2, and it is 56 bytes in.
my $offset = (split)[0] - 56;
# Only report potential superblocks on sector boundaries.
if (int($offset / 512) == $offset / 512) {
printf("%8d %8d %8d\n", $offset, $offset / 512, $offset / 1024);
}
}
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