[gentoo-amd64] Re: Recover files on ext4 partition

[Duncan]

Paul Hartman <paul.hartman+gentoo@×××××.com> posted
58965d8a0907081341i22045daasaef92f2bd21d4da0@××××××××××.com, excerpted
below, on  Wed, 08 Jul 2009 15:41:53 -0500:

> On Wed, Jul 8, 2009 at 3:16 PM, Bernhard
> Auzinger<nordpolcamper@×××××.com> wrote:
>>
>> does anyone of you have some experience in recovering a wiped out ext4
>> partition?
>>
>> I accidentially ran "mkfs.ext4" on a ext4 partition for which I do not
>> have a backup (I wanted to format sdg but instead I accidentially took
>> sde :( ).
>>
>> Is there a way to recover the data in this case?
>>
> Oh man, I'm really sorry to hear that. The first advice before trying
> anything is to get another hard drive or partition and make a clone or
> image of the partiton, in case attempting to repair it actually damages
> it worse.

I'd reemphasize that again.  The first rule in such a recovery is take an 
image and work with it, so you don't make the problem worse.

dd or dd-rescue (which works better in the case of physically damaged 
hardware, but shouldn't matter so much here) is the usual imaging tool.  
Just be SURE you're pointing it at the correct write location.

Beyond that, I'd suggest contacting the maintainer (Ted Ts'o) himself, or 
more accurately, the ext4 list (much better than mailing an individual 
for something like this), as ext4 is new enough and different enough from 
ext3, it's unlikely there's standard recovery tools out there for it yet.

If it was a conversion from ext3, you can probably still get most of the 
original ext3 files back at least, using ext3 recovery tools to do so, 
but may not get anything updated since then.  If it was originally ext4, 
that list is very likely to have tools they used in testing that will be 
quite helpful.  They'll almost certainly have some technique hints for 
you, as well.

From the /usr/src/linux/MAINTAINERS file (snipped and reformatted for 
posting):

P: Person
M: Mail patches to
L: Mailing list that is relevant to this area
W: Web-page with status/info
T: SCM tree type and location.  Type is one of: git, hg, quilt, stgit.
S: Status, one of the following:

   Maintained: Someone actually looks after it.

F: Files and directories with wildcard patterns.
   A trailing slash includes all files and subdirectory files.
     F: drivers/net/  all files in and below drivers/net
     F: drivers/net/* all files in drivers/net, but not below
     F: */net/*       all files in "any top level directory"/net

EXT4 FILE SYSTEM
P:      Theodore Ts'o
M:      tytso@×××.edu
P:      Andreas Dilger
M:      adilger@×××.com
L:      linux-ext4@×××××××××××.org
W:      http://ext4.wiki.kernel.org
S:      Maintained
F:      Documentation/filesystems/ext4.txt
F:      fs/ext4/

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman