# Memory card failure?

Started 3 months ago | Discussions thread
Re: Memory card failure?

JasonTheBirder wrote:

Overrank wrote:

JasonTheBirder wrote:

David Pavlich wrote:

JasonTheBirder wrote:

Let's say for illustration purposes, the probability of a single card failing over the typical use case of a photographer was 1/100000. (One in a hundred thousand). Now let's say every photographer uses about twenty cards in their lifetime. Then the probability that a given individual photographer will face at least one card failure is approximately

1 - (99999/100000)^20 = 0.00019998... ~= 1/5000.

If there are a million photographers, that still leaves an expected value of 200 unlucky photographers out there, even though most of them will be oblivious to the problem.

Not bad odds.....unless you happen to be one of the 200 and hopefully this person had a second card slot.

David

True, I suspect whatever the probability of failure is for cards under spec, it is a lower bound due to other factors like physical damage, overuse, using in tough weather etc. But yes, I think memory cards are on average really reliable.

Remember that that 1/100000 probability of failure is a number plucked out of the air - it could be 1 in 10 or one in 10^12 ..... unless someone has a reference for card failure rates ?

Ah I think it's really hard to estimate. There was a site I found once with numbers but now I can't find it. But thanks for pointing that out. My goal was not to try and calculate exact numbers but to show that even with a really small chance of failure, there will still be some people that will experience it.

I thought that was what you meant, but I thought I’d better reinforce it. I suspect the probability of failure will vary with card manufacturer, with capacity, with technology etc etc.

It will also likely follow a “bathtub curve” where you have quite a lot of failures when new, then few failures, then more failures when old. People with a high rate of use (eg professional photographers) will replace their cards frequently and so won’t see failures, and people with a low rate of use won’t use it enough to see the failures either

I’ve only had failures/problems with new cards, and I understand how to handle potentially static sensitive components

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