On 01/06/2013 05:26 PM, Goffredo Baroncelli wrote:
> Hi Chris
[...]
>
> I will start to update the wiki; then I will give a look to wipefs to
> improve it.
Hello I updated the wiki page:
https://btrfs.wiki.kernel.org/index.php/Problem_FAQ#What_if_I_don.27t_have_wipefs_at_hand.3F
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What if I don't have wipefs at hand?
There are three superblocks: the first one is located at 64K, the second
one at 64M, the third one at 256GB. The following lines reset the magic
string on all the three superblocks
# dd if=/dev/zero bs=1 count=8 of=/dev/sda seek=$((64*1024+64))
# dd if=/dev/zero bs=1 count=8 of=/dev/sda seek=$((64*1024*1024+64))
# dd if=/dev/zero bs=1 count=8 of=/dev/sda seek=$((256*1024*1024*1024+64))
If you want to restore the superblocks magic string,
# echo "_BHRfS_M" | dd bs=1 count=8 of=/dev/sda seek=$((64*1024+64))
# echo "_BHRfS_M" | dd bs=1 count=8 of=/dev/sda seek=$((64*1024*1024+64))
# echo "_BHRfS_M" | dd bs=1 count=8 of=/dev/sda
seek=$((256*1024*1024*1024+64))
------
>
> BR
> G.Baroncelli
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