[TriLUG] saving extended partition info

[tomed at bellsouth.net]

dd, AKA Data Destroyer.

Tom Ed

At Sun, 22 Apr 2007 09:33:16 -0700 (PDT),
Joseph Mack NA3T wrote:
> 
> On Sun, 22 Apr 2007, Alan Porter wrote:
> 
> >
> >> I save the first 512bytes of a disk (the mbr) with dd
> >
> > I would feel a lot more comfortable with something like
> >
> >   fdisk -l > fdisk.out
> >
> > Recovery is a little harder, because I'd have to type in some
> > numbers.  But copying raw bytes from the hard disk is just
> > not transparent enough for me.  I prefer a method where I can
> > use "vi" to view and edit the information in human-readable
> > format.
> 
> that's what I'm looking for too.
> 
> As for recovery: yesterday I dd'ed a windows disk image onto 
> /dev/hda (my main disk) instead of /dev/sda (my usb backup 
> disk). It took me about a minute to realise that the light 
> wasn't going to come on on the usb backup disk, to figure 
> what I'd done and kill the dd. fdisk showed I now had a 
> partition table for a windows disk on my linux machine. The 
> machine was still happily running and so I dd'ed my copy of 
> the original mbr back onto the linux disk, to find that 
> everything (including the extended partitions) was still 
> available except /dev (all garbage) and I'd lost a few files 
> in /root. /etc and all other directories in / were fine.
> Presumably the files in /dev were closet to the start of the 
> disk, followed by /root.
> 
> I let all my other jobs complete, shut the machine down and 
> moved the disk to a new machine were I found only the / 
> partition to have problems. I should have fsck'ed using one 
> of the alternate superblocks, but I used the standard one 
> and wound up with a hosed partition, which I restored from 
> the previous night's backup.
> 
> I'm now trying to figure out how to recover disks if I 
> deliberately `dd if=/dev/zero` to the start of the disk.
> 
> Joe
> -- 
> Joseph Mack NA3T EME(B,D), FM05lw North Carolina
> jmack (at) wm7d (dot) net - azimuthal equidistant map
> generator at http://www.wm7d.net/azproj.shtml
> Homepage http://www.austintek.com/ It's GNU/Linux!
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