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Date:   Thu, 30 Apr 2020 16:03:09 +0200
From:   Lukas Czerner <lczerner@redhat.com>
To:     Filip =?utf-8?B?xaB0xJtkcm9uc2vDvQ==?= <r.lkml@regnarg.cz>
Cc:     linux-ext4@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>
Subject: Re: Any way to dump ext4 filesystem without file data blocks? (for
 later analysis)
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On Thu, Apr 30, 2020 at 03:44:09PM +0200, Filip =C5=A0t=C4=9Bdronsk=C3=BD=
 wrote:
> Hello,
>=20
> I have experienced several mysterious ext4 issues on remote machines
> with poor internet connection (mobile broadband) that are not easily
> physically accessible.
>=20
> I would like to download the filesystem image from the remote machine
> for local investigation but the partition is rather large (500GB in
> one instance) and I cannot easily upload that much data over the
> mobile connection.
>=20
> Is there any way to extract only filesystem metadata (superblock,
> inodes, directory data blocks, etc.) from the partition but not
> file data blocks? Ideally so that I could then reconstruct an
> identical filesystem image, only with file data blocks zeroed out.
>=20
> It seems it should be straightforwad to write such a tool but before
> I start doing so, I wanted to check whether somebody hasn't already
> written one. (It seems this might be a common enough need when
> debugging and developing filesystems.) Short googling around and
> searching list archive did not reveal anything.
>=20
> Thanks for any pointers.
>=20
> Filip Stedronsky

Hello Filip,

indeed there is a tool exactly for this purpose. It is called e2image
and it's part of the e2fsprogs. The manual page also have some useful
examples of how to use it.

Good luck.

-Lukas