[ILUG] Can an ILUG guru save me?

[Timothy Murphy]

On Saturday 05 March 2005 06:18, Brian Foster wrote:

>  not exactly an alternative superblock, but close:
>   a trick which saved me many times yonks ago back
>  the volatile superblocks days was similar to:
>
>     mkfs /tmp/file original_size
>     dd if=/tmp/file of=/dev/dead_fs count=1
>     fsck /dev/dead_fs
>
>  which (re-)constructed the original superblock,
>  installed it over the corrupted superblock, and
>  then tried to patch things up.

Thanks very much for this suggestion,
which seems intriguing.

But I'm not entirely clear what you are doing..
What exactly is original_size?
What will tmpfile contain? And what size will it be?
"man mkfs" on my system (Fedora-3) only suggested the above usage
when /tmp/file was the mount-point for a file system.

Incidentally, is the superblock the first block?
I looked at the filesystems on my laptop with od,
and they all had 02000 (octal) 0's at the start.
The following block looked as though it might be a superblock.
The version on the bad file-system differed slightly
from the other file-systems, all 10 of which seem OK,
according to fsck.
It looked as though a magic number might be wrong.



-- 
Timothy Murphy  
e-mail (<80k only): tim /at/ birdsnest.maths.tcd.ie
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland