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Our old SanDisk CompactFlash 256MB card died recently, during a photo session. My wife was taking photos with it - sometimes in humid environment -, then as she was browsing through the results on her laptop via a card reader, all of a sudden the next picture just came out a small rectangle in the middle of the screen. And then the next didn't come at all, and after that neither the laptop nor the camera could recognize the memory card anymore.

Luckily I found PhotoRec via a couple of posts here, and it saved our weekend - I could backup most of the (over 200) pictures from the card, but my wife says some of the earliest are missing. Then I tried to reformat the card, but it failed.

To me this looks like somehow the first sectors on the card got permanently damaged. All this makes me wonder, what could be the reason? As memory cards contain no moving parts, I always assumed they could live practically forever. Can anyone make a guess about this particular case, or give an explanation about the typical causes and ways of memory card failures?

Update: I forgot to mention that the card was not heavily used and it is approx. 8 years old, so I don't think it could have been written to more than maybe a couple of thousands of times.

"Humid environment" meant being in a sauna for a couple of minutes, not underwater :-)

Péter Török
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2 Answers2

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Memory Cards (or SSDs) have something called "write endurance" which limits the number of times you can write to them. A search for this term or "write limit" will bring up a lot of pages which will give you a lot more detail, but basically:

The number of write cycles to any block of flash is limited - and once you've used up your quota for that block - that's it! The disk can become unreliable.

Source

It's usually quite a large number, but I would assume that it could be affected by things like temperature, humidity, shocks etc.

I would work on the assumption that the drive could fail at any time. Keep it backed up and always carry a spare.

ChrisF
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Flash has a limited number of write-cycles, measured on the order of 10000 to 100'000 writes. Some cards have controller logic to mark and avoid segments that have gone bad, but flash will ultimately fail. Environment likely had little to do with it (unless "humid" meant "underwater" or "with heavy condensation dripping off everything").

msw
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