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I have rescued my 2gb usb stick in nearly two days onto an 100gb blank reiserfs partition with these two commands:

ddrescue -f -n /dev/sda /dev/sdb8 logfile

ddrescue -d -f -r3 /dev/sda /dev/sdb8 logfile

since I did not know what to do next, I tried mounting /dev/sdb8 to look what's inside. But mount: you must specify the filesystem type. Before that I was able to mount the blank reiserfs partition before ddrescue wrote on it. Is there a way to read the rescued data now?

Thanks.

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2 Answers 2

Most USB sticks use the PC partitioning format, and have a single partition. That means the first sector (512 bytes) of the disk contains a partition table (and optionally a bootloader), and the rest of the disk contains the partition.

You could have rescued just the partition with

ddrescue -f -n /dev/sda1 /dev/sdb8 logfile
ddrescue -d -f -r3 /dev/sda1 /dev/sdb8 logfile

But now that you have the whole disk, you can get at its partition.

losetup -o 512 /dev/loop0 /dev/sdb8
mount -r /dev/loop0 /mnt

If /dev/loop0 is already in use, you may have to choose another number. The command losetup -f will return the number of a free loop device.

However, manipulating partitions on a live system is error-prone, so rather than do this, I recommend moving the data from the USB stick to an ordinary file. Either copy the whole disk, then use losetup on the disk image (16M × 130 is calculated to be larger than the size of the USB stick):

dd bs=16M count=130 </dev/sdb8 >/var/tmp/usb-stick.disk

Or copy just the partition, and mount the partition image directly:

tail -c +513 </dev/sdb8 | dd bs=16M count=130 >/var/tmp/usb-stick.partition
mount -o loop,ro /var/tmp/usb-stick.partition /mnt

And for future reference, you might as well have passed an output file, rather than an output partition, to ddrescue in the first place.

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hi! Cannot mount -r /dev/loop0 /mnt mount: you must specify the filesystem type so I gave mount -r -t usbfs /dev/loop0 /mnt a try and it worked, but the content was weired...four folders 001 002 003 004 and a textfile 'devices' ? –  panny Nov 13 '10 at 22:21
    
@panny: usbfs is a pseudo-filesystem (like proc and sysfs); it ignores the device. What you have is probably a vfat filesystem, but if mount didn't figure out the filesystem automatically, there's probably something wrong elsewhere. How exactly did you create the loop device? What does file - </dev/loop0 show? What about file - </what/you/ran/losetup/on? –  Gilles Nov 13 '10 at 22:29
    
file - </dev/loop0 shows /dev/stdin: DOS executable (device driver) and file - </dev/sdb8 shows /dev/stdin: DOS executable (device driver). I would ddrescue the whole 2gb again with proper arguments etc., but it took - don't know why - nearly two days to finish :/ –  panny Nov 13 '10 at 22:40
    
#parted /dev/sdb8 unit B print Warning: GNU Parted has detected libreiserfs interface version mismatch. Found 1-1, required 0. ReiserFS support will be disabled. Error: /dev/sdb8: unrecognised disk label –  panny Nov 13 '10 at 22:42
    
I created the loop filesystem like: losetup -o 512 /dev/loop0 /dev/sdb8 –  panny Nov 13 '10 at 22:45

you copied a disk to a partition - this is why there is a difference
if you wanted to mount the partition by itself to mount normally you should have used /dev/sda1 as the input file

you need to carve the partition out of the disk-file or use offsets for mounting tutorial:
http://www.andremiller.net/content/mounting-hard-disk-image-including-partitions-using-linux

you should also be able to easily see the contents with autopsy/sleuthkit available via apt-get or as rpm from CERT.org

typically i copy a disk or partition to a file...it's just easier to work with that way. then if i copied a disk to a file a carve the partitions into individual files or mount them like in the previously stated tutorial. last i have partition files i can mount and cp -pR to new partitions.

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