We've had no problems using ddrescue on the Mac.  You should be sure to image 
the drive itself as listed in Disk Utility and not the volume.  Additionally, 
on the Mac, you don't need to duplicate the image, and you don't need to image 
it to a drive in order to use it.

To create the image, use something along these lines on a Mac:

sudo ddrescue /dev/rdisk0 image.dmg logfile.log

(plus whatever other flags you feel like using).

In order to attach the image so that you can run a tool like Disk Warrior, but 
still not have to worry about modifying the original disk image file, do 
something along these lines:

hdiutil attach -nomount -noautofsck -noverify image.dmg -shadow

The "-shadow" flag puts all the changes made in a separate file.  Whenever you 
mount the image from then on, you'll need to mount it using the -shadow flag at 
the command line.

Now run Disk Warrior or Data Rescue III or whatever you deem necessary to get 
the actual data out of the image.


-- 
Hank Schultz
Apple Certified Macintosh Technician
Charlotte Street Computers
252 Charlotte Street
Asheville, NC  28801
828-225-6600

Become our fan on Facebook - find out about contests, giveaways, and the latest 
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On May 18, 2012, at 5:39 AM, James Wilson wrote:

> Hi Nate,
> 
> I recently had to utilise the amazing ddrescue to recover an encrypted 3TB 
> FileVault2 drive.  The image alone took 2 weeks to create, so I feel your 
> pain!  Mounting the DMG via Finder was problematic, however via the console 
> gave more positive, but mixed results.
> 
> I ended up, as suggested by Felix, writing the image back to a known good 
> drive via a CentOS 6.2 box.  This worked perfectly, using the command:
> 
> ddrescue -v --block-size=4KiB ./sda.dd /dev/sda recovery_drive.log -f
> 
> In order to help you, could you provide the following information
> 
> - What version of ddrescue?
> - What command line syntax did you use to create the image?
> - Was the drive a single partition, using HFS+?
> - How did you try and mount the image, via Finder or the console?
> - If the console, what was the command used?
> 
> Kind regards,
> 
> James
> 
> 
> On 18 May 2012, at 09:18, Felix Ehlermann wrote:
> 
>> Dear Nate,
>> 
>> I think you might be writing to the wrong list, but I can give you a few 
>> generic advices, hoping that they will be of help to you:
>> 
>> * If you create an image from a damaged drive, DO NOT perform 
>> repair-operations on this image, but make another copy (e.g. dd the image 
>> onto a working drive) and try to repair that copy. This way you will not 
>> lose additional data if your repair tool screws up, because your first (44 
>> hours worth) copy is still preserved without any additional damage.
>> 
>> * It is not obvious to me which instructions you were following, and it is 
>> also possible that you made a mistake when typing / copying the commands - 
>> so in general its a good idea to provide the command line you ran and maybe 
>> some output (was all data recovered? were there unreadable sectors? etc.). 
>> This way people can better understand what you did and give you more 
>> specific support.
>> 
>> Regarding your problem to open the dmg-file I would assume that you maybe 
>> copied the entire drive's content into the image - including the partition 
>> table. This might prevent the dmg-file from being directly accessible 
>> (because the partition table is 'in the way'). The error message seems to 
>> indicate a different cause (as it doesn't complain about the content of the 
>> file but about an i/o-error), but (fortunately) our Mac customers didn't 
>> provide me with this kind of problem yet, so I don't have further 
>> suggestions on this.
>> If my guess about the partition table is correct, you might be able to 
>> access the data after copying the image back onto a working drive - but (as 
>> you didn't provide additional information) it's of course also possible that 
>> a major part of the drive was not readable and you will need to repair the 
>> filesystem structure first. For that you will need tools other than ddrescue.
>> 
>> 
>> Kind Regards
>> Felix
>> 
>> On 16.05.2012 18:45, Nate Wood wrote:
>>> 
>>> Not sure if this is the right forum to ask as this is not a bug so I 
>>> apologize if it is not.  Just desperate for help at this point.
>>> 
>>> I used ddrescue for a Mac server and created a 445GB .dmg file as the 
>>> instructions showed how.  However, when I continue the instructions and try 
>>> to mount I get this error:
>>> 
>>> mount_hfs: Input/output error
>>> 
>>> 
>>> I can do some digging of course and will but after waiting 44 hours for 
>>> this file to be created my heart sank when I got this message.
>>> 
>>> If anybody can help I'd appreciate it.  And if this the wrong forum please 
>>> let me know that too.
>>> 
>>> Thanks.
>>> Nate
>>> 
>>> 
>>> _______________________________________________
>>> Bug-ddrescue mailing list
>>> [email protected]
>>> https://lists.gnu.org/mailman/listinfo/bug-ddrescue
>> 
>> _______________________________________________
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> 
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