Date: Sun, 13 Feb 2011 21:24:57 +0000 From: Alexander Best <arundel@freebsd.org> To: Anders Andersson <pipatron@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: Recover a ufs2 filesystem from a reformat with another ufs2 filesystem Message-ID: <20110213212457.GA26171@freebsd.org> In-Reply-To: <AANLkTikSTgcsVnjRuF2Un4oBXfYaYy0r_o%2BgKzcRmkrX@mail.gmail.com> References: <AANLkTikSTgcsVnjRuF2Un4oBXfYaYy0r_o%2BgKzcRmkrX@mail.gmail.com>
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On Sun Feb 13 11, Anders Andersson wrote: > 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? i'm no expert, but the very first thing your friend should do probably is 1) boot from a freebsd bootable dvd / memstick 2) dd if=/dev/overwritten_hdd of=/file/on_another_huge_hdd bs=1m 3) physically disconnect the overwritten hdd and do all further experiments via mdconfig(1). good luck. alex > > Anything helps! > > // Anders -- a13x
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