Recover failed SD card

Bruce Ferrell bferrell at
Sat Feb 23 21:41:37 UTC 2019

On 2/23/19 11:47 AM, Valeri Galtsev wrote:
> On 2/23/19 10:50 AM, Andrea Venturoli wrote:
>> Hello.
>> A customer of mine gave me an SD card which is quite surely failing.
>> I'm trying to recover what I can.
>> I first tried using an USB based reader: altough the SD card should 
>> be 4GB in size, dd just copies 121MB. So does recoverdisk.
>> "camcontrol readcap /dev/da3" gives:
>>> Last Block: 248319, Block Length: 512 bytes
>> which agains means about 121MB.
>> I put the card in another box and i get:
>>> mmcsd0: 127MB <SD  0.0 SN 00000000 MFG 00/0000 by 0x0000> at mmc0 
>>> 0.4MHz/4bit/65535-block
>> Is there any way I can get beyond this 121-127MB limit and read what 
>> I can of the rest?
>> I looked into camcontrol's man page, but came up with no idea.
> I would be sceptical about that. The card is a single chip, not even a 
> printed circuit board, so whatever the failure it is it is inside the 
> chip (read: integrated circuit). Yet, out of desperation, I would try 
> what we did with failing printed circuit boards: put it for some time 
> in a freezer (say for 20-40 min), take it out and try to read again. 
> Heat moderately, I would say to about 90 C (for about 20-40 min), and 
> try to read it again.
> Next step is paid recovery services, with those stay away from the 
> ones who charge even for "taking a look", use only those who charge if 
> they recover most of the stuff. These will be expensive, expect to pay 
> $500 - $1000. Ask me off the list which ones I know are good just by 
> someone's I know experience. The cases I know of were hard drives, but 
> some of them may work with Flash devices as well.
> Good luck!
> Valeri
>> The card should hold pictures, so I could go ahead with photorec once 
>> I got an even partial image.
>>   bye & Thanks
>>      av.
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Unfortunately flash memory "wears out".  There are spare storage blocks 
and logic to level wear by switching th the spares when main block 
failures are detected.

More expensive devices set themselves read only before ultimate failure 
happens.  From what you describe, this one isn't on of them so now there 
is data loss and no way to recover.

this isn't a matter of removing the spinning rust media and mounting 
into a "jig" to recover from (in the old days recovery services 
advertised clean rooms to do this).

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