Recover failed SD card

Valeri Galtsev galtsev at
Sat Feb 23 19:47:27 UTC 2019

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!


> 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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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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