copying a disk with ignoring errors

[Christoph Kukulies]

Am 06.01.2010 02:30, schrieb Polytropon:
> On Tue, 05 Jan 2010 15:31:46 +0100, Christoph Kukulies<kuku at kukulies.org>  wrote:
>    
>> It copies a disk sector by sector to a file (kind of dd), but ignores
>> errors, it just skips sectors it couldn't read (after a couple
>> of retries). The result was, that one had a - albeit - worm-eaten -
>> image of the disk allowing to access the filesystem
>> and getting to the important files with a little luck these not being
>> amongst the corrupted data.
>>
>> Anyone knowing what this little tool was named? Something like diskcopy,
>> devcopy, I forgot.
>>      
> > From my "list" of recovery-related tools:
> 	dd_rescue
> 	ddrescue
> 	fetch -rR<device>
> 	recoverdisk
>
> I'm quite sure it was one of them.
>
>    


Allow me to followup on this a bit vintaged thread but it's an all over 
again happening issue.
Some student lost some important data due to disk failure.

I tried PHKs' recoverdisk with  recoverdisk -b 1024000 /dev/ad2 ad2.dmp

and it went off quite promising just few dma read timeouts and when I 
was at 7% of recovery
it suddenly says:
ad2: FAILURE - device detached.
1558528000 1024000 failed (device not configured)
#

Hmm. How can I avoid that the device gets detached?

--
Christoph