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Date:      Fri, 28 Jun 2013 21:39:12 +0530
From:      KK CHN <kkchn.in@gmail.com>
To:        Polytropon <freebsd@edvax.de>
Cc:        freebsd-questions <freebsd-questions@freebsd.org>
Subject:   Re: Retrieving a FreeBSD installation
Message-ID:  <CAKgGyB-dH+wbxCZGnSMKuMoAoHZqVkLaUP=Cr_WpX51a1p3byA@mail.gmail.com>
In-Reply-To: <20130627094717.a3bab5aa.freebsd@edvax.de>
References:  <CAKgGyB_QzfunV_4jVZ+A_rAtvVf7SfEeL=taiuoVvVwCX6SZew@mail.gmail.com> <20130627094717.a3bab5aa.freebsd@edvax.de>

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On Thu, Jun 27, 2013 at 1:17 PM, Polytropon <freebsd@edvax.de> wrote:

> On Thu, 27 Jun 2013 07:28:49 +0000, KK CHN wrote:
> > List,
> >
> >   I accidentally installed  a Linux variant(mint OS) on my Harddisk
> > where  FreeBSD is installed( which contains my data).
> >
> > Is there a  possibility  to retrieve that FreeBSD Installation which
> > is overwritten by Linux installation.
>
> In most cases: What has been overwritten is lost.
>
> But: What has "only" been disallocated (data still on disk)
> can _sometimes_ be recovered.
>
> So it depends on _what_ is still left.
>
> Anyway, do not do anything with the disk. Do not try any
> recovery on the disk itself. Make an image of the disk and
> use that image file for any further action. In case you
> damage it, make a new copy. Only work with copies. One wrong
> step can massively decrease your chances of recovery.
>
>
>
> > Any hints  welcome!
>
> It will be a very hard thing. You will probably have a lot
> of "trial & error" experience, and you will surely learn a
> lot, for example about file systems.
>
> I've written about this topic on this list already, and I
> will again re-use some details from a previous post to make
> a list for what you can try.
>
> Boot from a live CD or USB stick or a different disk. Then
> make a copy of the disk using
>
>         # dd if=/dev/ad0 of=disk.dd
>
> where /dev/ad0 is the disk you have accidentally overwritten
> your OS installation. In case the disk makes any trouble, use
> dd_rescue or ddrescue (from ports).
>
> You can also try this:
>
>         # fetch -rR /dev/ad0
>
> Also recoverdisk could be useful. Maybe there's enough information
> left to re-instantiate the file systems? Also try testdisk.
>
> When no file system can be re-instantiated, but you're sure
> your data is still somewhere, you can use photorec for recovery.
> It is able to recover a lot more than just photos.
>
> The ports collection contains further programs that might be
> worth investigating; just in case they haven't been mentioned
> yet:
>
>         ddrescue
>         dd_rescue       <- use this to make an image of the disk!
>         magicrescue
>         testdisk        <- restores content
>         recoverjpeg
>         foremost
>         photorec
>
> Then also
>
>         ffs2recov
>         scan_ffs
>
> should be mentioned.
>
> And finally, the "cure to everything" is found in The Sleuth Kit
> (in ports: tsk):
>
>         fls
>         dls
>         ils
>         autopsy
>
> Keep in mind: Read the manpages before using the programs. It's
> very important to do so. You need to _know_ what you're dealing
> with, or you'll probably fail. There is no magical tetroplyrodon
> to click ^Z and get everything back. :-)
>
> Proprietary (and expensive) tools like "R-Studio" or "UFS Explorer"
> can still be considered worth a try. Their trial versions are for
> free. "UFS Explorer" even works using wine (I've tried it).
>
> If you can remember significant content of your data, you can
> even use
>
>         # grep <pattern> disk.dd
>
> to see if it's still in there. With magicrescue, you can try
> something like this:
>
>         # magicrescue -r /usr/local/share/magicrescue/recipes -d out
> disk.dd
>
> where out/ is the directory where your results will be written to.
> Keep in mind that _this_ approach will _not_ recover file _names_!
>
>
>
>
> I know how bad it feels for such a "simple" mistake and I
> won't make fun on you, pointing you to use your backups.
>
> Of course you always have the option to send your disk to a
> professional recovery company. This substitutes learning and
> trying yourself by impressive amounts of money. ;-)
>
>
>
> Good luck!
>
>
Thank you very much, I am going to invest my time to try the valuable tips
you shared. I admit the wrong step I made. Thanks again.

>
> --
> Polytropon
> Magdeburg, Germany
> Happy FreeBSD user since 4.0
> Andra moi ennepe, Mousa, ...
>



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