| 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
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
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