Totus Copy, for your dying hard drive

The macosxhints article was written before GNU ddrescue was developed.

I would not recommend using dd. There are many drawbacks with using dd. It's slow even on the error-free stuff since it's doing tiny reads and writes. It spends a lot of time chewing through the erroneous parts of the drive, rather than reading as much error-free stuff as it can, THEN going back to do the hard stuff.

The GNU ddrescue first recovers data from all the good sectors on the drive and then goes back and tries to recover data from the bad sectors on the drive. You will likely recover more data this way. If you try to recover data from bad sectors before all the data on the good sectors has been recovered, you risk losing the data on the good sectors if the drive hardware is failing.

Another advantage of GNU ddrescue is that it enables you to do multiple passes to recover your data. For example:

# first, grab most of the error-free areas in a hurry:

ddrescue -B -n /dev/rdisk0 /dev/rdisk1 rescued.log

# then try to recover data from the bad sectors without pushing the drive too hard:

ddrescue -B -r 1 /dev/rdisk0 /dev/rdisk1 rescued.log
(the "-r 1" is necessary to make it retry the failed areas up to 1 time)

# then try to recover as much of the dicy areas as possible:
ddrescue -B -r 10 /dev/rdisk0 /dev/rdisk1 rescued.log
(the "-r 10" is necessary to make it retry the failed areas up to 10 times)

There is agood interview with the developed of GNU ddrescue here:
http://blue-gnu.biz/content/interview_gnu_ddrescue_039_s_antonio_diaz_diaz

System requirements: "A failing hard disk that still mounts".

Ah yeah not that good ddrescue and plain old dd dont have that limitation, If the device attaches bus and can be seen at /dev/diskX , You will be able to image the whole drive or just one partition.

Then mount the image and then fix the filesystem.

See: http://www.macosxhints.com/article.php?story=20050302225659382

@Kyle,
I'm talking about a device level image not an OSX image. I'm not saying Totus isn't a good tool, but when a device is failing you have to triage. As I said earlier, if a there are a few key files then Totus could be a good solution, but if you need maximum recovery then you should make a device level image. For really damaged disks, hardware level reverse cycle clone may be efficacious, but that is not a consumer end-user feature--well, at least not until it is bundled with the tools needed to extract data from the clone.

This app may help you copy some files off but if your disk is failing you are better off using Drive Genius and Data Rescue II to make a disc image and recover from the image of the drive. Totus might be helpful if you have one critical file you need to get off but if you need to recover more than a few files you should make a single pass to image the disc and then work with recovery software on that.

If you really have a dying drive and have access to a pc and can remove the hard drive, spinrite (from grc.com) is the answer for you.

What about software solutions for drives that don't mount in the OS?

mark, you're missing the point. Brett, the author of this post is not the person who wrote the program. I'm sure the program's developers have smashed many a hard disk then used their program on it.

Paying for a program that hasn't even been tested once? No thanks. You should be grateful for beta tester results, and not be charging them.