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Date:      Mon, 6 Aug 2012 09:08:58 +0200
From:      Polytropon <>
To:        Matthew Navarre <>
Subject:   Re: Mounting raw disk backup file.
Message-ID:  <>
In-Reply-To: <>
References:  <>

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On Sun, 5 Aug 2012 23:12:48 -0700, Matthew Navarre wrote:
> I can probably fix the partition table using testdisk, but now that I've
> got this image file I'd rather work with that instead of the physical disk.
> I've read the Handbook section on using mdconfig, but that assumes the
> image file is of a filesystem, not a whole disk. I think I've
> found instructions for how to do it on linux, but if there's a way to mount
> it on FreeBSD I'd rather do that.

It depends on _what_ your disk image (typically created by a
dd-like utility to make a 1:1 copy of a whole disk) contains.
If there are several slices and partitions, each of them can
be accessed like it was a physical disk.

Let's assume you have /home/you/ada1.dd which is the copy of
your former /dev/ada1 disk. You do:

	# mdconfig -a -t vnode -u 0 -f /home/you/ada1.dd

This results in a file /dev/md0 as well as any "partitional
qualifier specials" that might correspond to the disk the copy
has been taken from. You can check that with

	# fdisk /dev/md0

and it should print the same partition table as for the real

Now you can access and mount from that disk image, e. g.

	# mount -t ufs -o ro /dev/md0s1a /mnt

as this maybe is the root file system of the 1st slice. Note
the use of "-o ro" in this case. If you have had partitioned
your system, you can "add" those partitions into a fully
accessible /mnt tree for that system disk, e. g.

	# mount -t ufs -o ro /dev/md0s1d /mnt/tmp
	# mount -t ufs -o ro /dev/md0s1e /mnt/var
	# mount -t ufs -o ro /dev/md0s1f /mnt/usr
	# mount -t ufs -o ro /dev/md0s1g /mnt/home

Note that unmounting must happen in the reversed order. If there
was another file system, e. g. for sharing with "Windows" stuff,
it's also possible to mount it:

	# mount -t msdosfs -o ro /dev/md0s2 /mnt/win

Of course you can access all slices and partitions independently.
That should be the best approach for recovering data.

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

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