Re: Help -- Data recovery
Quoting Martin Bishop (martinbishop@crosswinds.net):
> Hi David,
>
> Thanks for replying.
>
> David Wright [d.wright@open.ac.uk] wrote:
> > I don't have the start of this thread anymore. You have linux on
> > this machine? If so, I'd try and mount the partition readonly from
> > linux rather than going anywhere near it with other OSes. I don't
> > think linux looks at the partition type, but only the magic.
>
> Yes I have linux on this machine (I'm dual booting Linux/Win98).
> Hmm, if linux doesn't care about the partition type, then does it
> care about the <file system> type?
Yes. If you think about it, only a dumb boot program requires
partition types and the bootable flag. A smart one will be
able to boot from the partition it's told to, but this requires
it to remember, or to have some sort of user interface built in.
But you can't recover files as files without knowing the system by
which the bytes are laid out in the partition. Ext2 filesystems
take this seriously and pepper the partition with backup copies of
the superblock. FAT doesn't.
> I'm asking this because hda2 was FAT32 (I accidentally deleted it
> and created a new partition on top as EXT2, same size, same
> partition type. And now I'm in panic mode and I'm trying to recover
> any data on hda2. That's basically the start of this threat.).
If it was a FAT partition, you will never mount it as ext2.
A serious data recovery person would, I imagine, dd the data off
the disk and then look for obvious structures like the top-level
directory which is in a fixed address after the FATs and the
superblock (or whatever the equivalent's name is). They might
have to reconstruct this block to make the filesystem mountable.
I guess you're not going to go that far, so you'll probably just
try mounting it is as all possible varieties of FAT.
dd'ing might get you a few large textfiles off a next-to-virgin
disk that has little fragmentation.
> > If you can mount it as whatever filesystem type works, then you can
> > copy out the data. If you can't, I can only guess that another OS has
> > vomited over part of it.
>
> Which <file system> do you suggest? EXT2? And is there a chance that
> this will further corrupt the data on it?
Just FATs. Mount it readonly and you won't be able to corrupt it.
(That's why I suggested a recovery person would copy it first.)
Cheers,
--
Email: d.wright@open.ac.uk Tel: +44 1908 653 739 Fax: +44 1908 655 151
Snail: David Wright, Earth Science Dept., Milton Keynes, England, MK7 6AA
Disclaimer: These addresses are only for reaching me, and do not signify
official stationery. Views expressed here are either my own or plagiarised.
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