Recover a ufs2 filesystem from a reformat with another ufs2 filesystem

[Anders Andersson]

Hi! I'm sorry if this has been brought up already but the search
function in the archives seem to be broken (since 2007?) so I couldn't
search for duplicates.

A short summary of my problem: I am trying to recover files from a
UFS2 file system that has been overwritten by a new UFS2 file system.

A longer problem description: I'm trying to help a friend recover from
a somewhat stupid mistake. He used a specialised distribution based on
FreeBSD (FreeNAS), that among other things can manage harddrives and
file systems. For reasons that he doesn't know, this tool formatted
his old partition with a new UFS2 file system when he attached it,
even though there was a perfectly fine one on the disk already. Now
I'm trying to recover the files from the old one, but a problem is
that the old one was also a UFS2 file system, so the tools I have
tried only finds the new one.

Now, being a linux guy with (unfortunately) very little experience of
any of the BSDs, I am trying this out in linux with the tools I have,
but it's not very easy. I don't know anything about UFS2 so I have
some questions:

1) If an old file system is overwritten by a new file system with the
same size, are there any traces of the old file system meta data left?
I'm thinking randomized backup headers scattered throughout the file
system, which would have a different location after each new format.
2) If there are no traces left of the old file system, would there be
any UFS2-aware recovery programs that could scan the disk and try to
regenerate the necessary meta data from, say, partition size, file
offsets, some other magic...?
3) Are there any powerful tools availaible for tasks like this in
FreeBSD that are not ported to Linux? In that case, I could easily
install FreeBSD in a virtual machine and salvage the files there.
4) If everything else fails, can you recommend a good overview about
UFS2, how and where the bits and pieces are stored on disk?

Anything helps!

// Anders