Elia Locardi is Back

How Often Do SD Cards Really Fail?

There's been enough dissections on how Canon and Nikon shot themselves in their respective feet by releasing mirrorless systems with only single card slots. Trust Tony and Chelsea Northrup, though, to spice things up a bit with some scientific analysis.

I know that this has been debated ad-nauseam, but I haven't actually seen any proper data on just how often the unspeakable happens. If anyone is a little tight of purse or just on the fence about it all, it helps to have solid figures to guide one in the right direction.   

The Northrups conducted a poll among their followers asking them their experiences with memory card failure rates. The poll, consisting of 4,344 people, while not a giant sample size, still seems like a size which one can pull some relevant data out of. And that's one of the things that I think this channel is best at. I always enjoy the Northrup's videos, but I find the more analytical ones to be almost always enlightening with regard to the more technical aspects of photography.

The arguments have gone back and forth over this, even on this website, but it's this kind of analysis that might actually sway people instead of one-off horror stories. I won't spoil the results by repeating them here, so please watch the video and share your thoughts below.

Mike O'Leary's picture

Mike is a landscape and commercial photographer from, Co. Kerry, Ireland. In his photographic work, Mike tries to avoid conveying his sense of existential dread, while at the same time writing about his sense of existential dread. The last time he was in New York he was mugged, and he insists on telling that to every person he meets.

Log in or register to post comments

4,300 is actually a pretty large sample size. The errors would be in the sampling and generalizability :) but I was a qualitative person that was never great at numbers haha

We cannot really take his findings seriously without being able to look at the setup of his survey. These results seem to only speak about the ability to experience a failure at some point and not at all about the frequency of failure or the number of people reporting their use of each type of card. These findings don't seem to point to any significant statement because yes... the more photos you take, the more likely you are to someday experience a failure. But this study seems to leave out any sample stat information that could have an affect on the results like how many people are using each storage format.

I'm not saying speaking to one side or the other in the argument... I'm just pointing out that as someone who works in marketing and has some experience in market research, this seems like a VERY flawed survey. Take his results with a spoonful of salt.

Hence my generalizability statement :) I was mainly saying that, provided a representative sample, 4,000+ is actually very large. I completely hear ya though.

Interesting, I'm in the 200k-500k group, but I'm not sure his data crunching is sound. I didn't see the survey, but to be fair to older formats, they should have only gone back 5 years at most. I've worked with thousands of CF and SD cards and the CF failed way more, but they were older tech. Both formats failed more in the past, and I'm sure they are both much better now. I've done some events that have required me to hot swap SD cards hundreds of times in a night without issue.

The bottom line is, redundancy is good. You just never know.

"Card failure" or rarity of is a strawman argument. Yes, cards fail, but rarely. The most common thing to cause loss of images is human error. Period.

Another strawman argument is, "back in the day, people only had one roll of film in their camera."

Yes, back in the day if you lost a roll of film you lost 36 images. In today's world losing a card can result in the loss of thousands of images.

It's objective common sense that having and using two cards in a camera will greatly mitigate the consequences of losing a card. Manufacturers releasing cameras with a single slot is stupid.

Having three slots would make it even more safe! Lets make it four!

Why are you being a blithering idiot? I know you think you're making some kind of point in a cleaver way, but you're not. Just one extra card can greatly mitigate the consequences of losing a card. Kind of like having one extra tire in your car can greatly mitigate the consequences of getting a flat.

Don't get so triggered by things you read on the internet.

Objective ruling states that having more than two card slots will mitigate the consequences of losing two cards. What I'd like to know is why you're so strongly against three card slots? We're talking about saving thousands of images here!

also, I've personally seen extra tires go flat...

Triggered? Nah, not triggered. Just observing that you're a blithering idiot. I'm not going to bother explaining why because it will simply open up a silly rabbit hole in which you're trying to take the conversation.

So instead of engaging you're just going to name call and tell yourself you're right about why every camera needs to have two card slots without taking a second to think outside of your seemingly entrenched point of view... sounds like you're already stuck in a hole. Would it be so horrible to consider that what YOU consider important on a camera isn't what everyone else cares about?

Look... Sony has been extremely successful with their mirrorless cameras that only come with one card slot. The rate of card failure is unclear because there isn't enough research to make a conclusive assessment so why should a camera company spend the extra money to put it into a camera that isn't their flagship pro camera line?

Again, stuck in the myopic canard of "card failure."


I will give you the point of name calling. I shouldn't have called you a name. I'm still good on calling your initial response as blithering idiocy, though. Even the most intelligent people can do and say idiotic things. Your first response to my post was idiocy. The bottom line is that redundancy is better than non redundancy. There is not rational argument against that.

It doesn't cost that much to add it. And it shouldn't take a "pro" camera classification to get it. My D750 was never marketed as a "pro" camera, but it has dual card slots. It's saved my bacon a few times. Only one failure, but the real saving of bacon has been human failure, ie MY idiocy. A couple of times I was an idiot and accidentally culled keepers. No biggie, my redundant card saved me. One time in a fit of idiocy, I handed my card with about 800 images on it to someone and we fumbled it, dropping it into a storm drain. No biggie, I had all the images on my secondary card.

Human error is the very reason your software asks you to confirm if you really want to delete that file or close a program without saving.

The point being is that in this day in age, there is no rational reason for camera manufacturers to not offer the option of a second card slot. Chastising those who reasonably call it out is idiocy.

I still disagree in the point that failure is not frequent enough to justify the production cost in a prosumer camera. We will just have to leave it as we both think the other is smoking something.

Well, It happened to me. Twice with an sdcard and once with the older memory card. Two times, the card failure wasn't of great significance but once I was after a school trip to Oxford. We visited a lot of colleges and it really hurt that my card fell apart.

In the case of Nikon Z7, probably the far more interesting polling question would be in order to get 2 card slot Z7, would you trade with 1) size and weight to get dual QDX? 2) lower fps to get QDX + SD ? 3) is QDX+Micro SD acceptable? 4) instead of QDX, having 2 SD slot.
Frankly, I would rather keeping existing Z7 size and weight and benefit of QDX instead of two card slots. QDX+Micro SD would truly be foolish. If enough people are truly concerned about having redundant backup, here is market for someone to make QDX version of Eye-Fi.

How much size and weight difference would there be with an added QDX? A few grams and at most a centimeter or two? Honestly I don't know, but I can't imagine it being more than 100 grams. For me, an extra 100 grams would make no difference.

Personally, I would absolutely sacrifice some FPS for redundancy. Of course, with what I generally shoot (portraiture) I can easily get by with 5 or 6ish FPS. Just having the option would be advantageous for both end user and for Nikon's marketing.

1) Yes 2) Yes 3) Yes 4) Yes
I'm a wedding photographer...

dont care about malfunction .. they are fragile (spilts in half, write lock gets broken, even gets stucked in camera), easy to lost, slower ... only upside is decent work laptops have SD card reader build into your laptop which is more comfy when working on the road ...
In 10+ years as photographer I had no damaged CF and as DIT I saw probably 2 not functioning CF cards that were old and from rental studio .. .

I’ve had four SD cards fail over the last ten years. They tend to fail most during high intensity writiting (shooting video, shooting bursts of stills). In each case the card becomes unresponsive and camera claims card error. Nothing short of formatting it can repair it. Data lost forever. Lexar has been good at replacing them due to lifetime warranty, but I much prefer my dual CF card setup.

A simple reformat will not destroy the data for good. It's astonishing to see how much "deleted" data one can extract with the help of rescue software.

Most or at least some of those ‘broken cards’ could likely just have had corrupt data headers (most beccause of an improper shut_down or power loss) that could have been repaired or at least the data could have been recovered with software like disk warrior, if they work after formatting nothing physical was actually broken

I am wondering how many of those that rant about single memory card slot cameras, do not have a tested and reliable backup strategy on their computer.

I similarly wonder how many people who argue that a single slot is no big deal also believe that not backing up your data once it's off the memory card is no big deal as well.

^^^ This. Those who regularly back up their data on a computer probably realize the importance of redundancy. It's actually kind of a no-brainer.

Two cards in three years. Each managed to record only about 15,000 before dying. Data on them could not be recovered and they could not be reformated either. They just died.

My opinion is that dual card slots is a bandaid for the bigger problem: SD Cards aren't very professional. Their failure rate is pretty high for something that would get used in a professional capacity.

Tony's data showed that SD cards had about 35% failure rate. Even if his data is skewed, that's still way off from yous expect from a high quality storage solution. To compare, Backblaze reported a 1.2% failure rate among their spinning hard drives in their data centers.

I honestly think it's time for SD Cards to be phased out for something more robust.

That was 35% of photographers, not cards. They might have had only one out of hundreds fail over the years. SD have also been around for a long time and many of those were most likely old hardware. His numbers are all but useless form a statistical comparison standpoint in regards to how the new cards perform.

Having 2 cards slot is not enough. You need to also insert the second card AND set it up as back up and not as an overflow option.

Realistically if you’re a pro, who are the people worried about one slot, you should be cycling out your cards on a regular basis. The failure rate within a year of purchase on professional cards only would make this useful.

Here's my take ... at some point, you will have a card fail. That's pretty close to a certainty, and even if it's not, it makes sense to act as though it were. It follows that you should backup early, backup often.

1. Writing to two card slots simultaneously is as early and as often as it's possible to get. If one card fails, you have the other.

2. I do a lot of travel photography. Each night I *always* backup the day's shots to TWO portable drives i.e. I have two complete sets of backup images for the entire trip. (When flying, one drive goes in checked baggage, one drive comes in carry-on.) You generally have a pretty good idea how many GB/day you shoot when travelling - have two portable drives with capacity for days-travel * GB/day plus an allowance of at least 30%.

3. When I download to my PC, all raw images are copied to local drives, and automatically synced to an attached NAS drive.

4. Post processing, all .PSD files are also automatically synced to the NAS drive. i.e. I protect the original images, and I protect the investment in post-processing.

5. Monthly I bring home a set of big (4TB +) portable drives from work. Using Microsoft's old but very reliable SyncToy, I do a "contribute" sync to these portable drives. i.e. these contain a complete history of every digital image I've ever taken, together with the corresponding PSD files. Once the backup is complete, *I take the drives back to work*.

If I'm at home and we have a fire, the first thing I'm going to grab is my wife, followed very shortly thereafter by the NAS drive, and get the hell out of there. If I'm not at home, I have the offsite portable drives. Other than family and memories, everything else is replaceable.

As a professional wedding photographer/videographer I will NEVER buy another camera unless it has 2 card slots. There are NO do overs in the wedding biz. My reputation is on the line here. Oops, my card failed is not an option. I love being able to tell my brides that both of my a7iii's have 2 card slots. This gives her peace of mind and me too!

And you use only one camera? I hope you do not shoot a wedding with only one camera.

You do realize that two cameras is no where near the same thing as having redundancy in card slots, right? Especially for a wedding photographer. Do you think they tote a couple of cameras around to take the same pics on each one?

You do realize that if you have only one camera and it fails you can’t take any photos, right?
Anything can fail; cards, cameras, lenses, flashes, batteries…
Highest risk: the photographer (human error), so you need at least a second shooter if “failure is not an option”.

So now you're talking about a second shooter. OK. Generally, as I understand it, a second shooter is not necessarily for redundancy in the case of card failure (again, the strawman argumen), but to get different/simultaneous shots. Though I'm sure a second shooter would come in quite useful in a case of lost data on a primary camera.

Many wedding photographers have a second camera on them; not for redundancy, but usually equipped with a different lens. It's not a redundancy thing. And, like I pointed out, a second camera does not mitigate losing data. Lost data on a camera's card is still lost data.

At the end of the day, a redundant slot in a camera is vastly better than not having it.

No, I’m talking about failure not being an option.
You have to look at all the risks. If card failure is the highest risk of not getting the shot(s), it makes sense to address it first, but I don’t think it is the highest risk. To have redundancy for small risks is fine, but if you haven’t addressed higher risks, failure will still happen.

You're obviously either not reading or unable to keep up. It's not the risk of of failure. It's the consequences of loss; either through failure, or more likely, human error. And the effort/cost of meaningful mitigation. Losing a card with a thousand images on it can be substantially consequential. That consequence can be greatly mitigated by a simple secondary slot. Not saying it's a guarantee, but it's greatly mitigated. For most people it will be enough. For others, they may want to take extra steps depending on their circumstances. The ratio of cost for a secondary slot to possible mitigation is such that not having a secondary slot is just stupid.

Kind of like having a spare tire. When's the last time you had a flat? I've NEVER had a flat tire while driving. But it's common sense to have a spare tire because the consequences of one of your tires going flat can be greatly mitigated by having a spare. No, it's not a 100 percent guarantee that you'll not still be stranded, but combined with the fact that tires rarely go flat, it greatly mitigates it.

I’m not reading or unable to keep up…
That’s what people say if they lack real arguments.

One spare tire will not reduce the risk of getting a flat, it will reduce the risk of getting stuck in the middle of nowhere (the consequence in your example). More than one tire can fail, so failure is still an option, but the chance of double failure Is way less, so we take the risk. Why not have two spare tires, or four, to reduce the risk even more?

Do you also have a spare car battery? Probably not. If your battery fails the consequences might be the same (getting stuck in the middle of nowhere). A car battery is not that big and not really expensive, so why do we all have a spare tire but no spare battery?
Talking about cars… Out of every 100,000 licensed drivers 16 die in a car accident. Low risk, high consequence. We all take the risk if we get into a car.

»The ratio of cost for a secondary slot to possible mitigation is such that not having a secondary slot is just stupid.«

Both Canon and Nikon have cameras (DSLR) with two card slots, so they know how to do it. The first two generations of Sony’s A7 series had only one card slot. If there was a simple low-cost solution, I think it would be there right from the start. It might not be that simple.

I have real arguments. It's just that you're not cognitively able to understand them. Then you blame me for lacking real arguments.

That accusation speaks more of you than anyone else.

The last word seems to be important to you, so I'll let you have it and leave this circular nonsense behind.

Have a good day.

Saying you have real arguments without providing them followed by insults and childish assumptions…
Really funny how some people project their own inability to have a grownup conversation onto others.

Did you read my post? Here is what I said, "I love being able to tell my brides that BOTH of my a7iii's have 2 card slots." So to answer your question, no, I use two cameras. Yes, they are BOTH on me at all times during the wedding day. I have the Tamron 28-75 on my left and the Sony 70-200 on my right. In a matter of seconds I can get a wide, medium and tight shot. This leads to more images being sold.

I find it funny nobody read your original post all the way thru. It's so obvious you use 2 a7iii's. Amazing how trolls can't even read a small paragraph properly

TOTAL NONSENSE! This is not even remotely useful "data."

First off, the participants self-selected themselves, and those (I'd bet a month's mortgage payment) a highly disproportionate of those who had failures responded, while an even larger disproportionately number of people who did not have failures did not bother to respond to such a nonsense survey.

Second -- Of those who say they had failures, I'd bet yet another mortgage payment that many NEVER actually had a failure. I know way too many people who have complained of card failures when it was really user error. (And one who complained that his card failed after the camera went into a fountain...)

I could probably come up with even more reasons this is pseudo-science, but those two already make the whole thing a joke, so I won't bother to continue.

SHAME ON FSTOPPERS for republishing something so misleading. You guys are better than this!

I disagree Burt. I used to work for the Australian Bureau of Statistics AND I have a double degree in Computer Science/Mathematics, so I'm qualified to speak on sample sizes. A few points:

1. 4300 is a pretty reasonable sample - if gathered and processed properly it would result in a highly reliable analysis.

2. Northrup himself is very careful to acknowledge that some of the stats may not be entirely supportable.

3. If you discard all else there is still one incontrovertible fact that comes from this sample: memory cards DO fail, just as disk drives do fail, and it has nothing to do with user error. That's not to say that sometimes it is attributable to user error, but it's totally illogical to assert that ALL card failures are attributable to that factor.

4. If it is possible for a card to spontaneously fail, even if the failure rate is < 1%, then it is madness not to take steps to mitigate the potential loss due to card failure.

It is a basic engineering probability problem. You should be able to compute the results. Two slots of a inferior SD memory device which fails at a higher rate than a XQD card, at some failure point, will be less reliable than a single higher reliability XQD. What is that number and did Nikon get it right?

»1. 4300 is a pretty reasonable sample - if gathered and processed properly it would result in a highly reliable analysis«

How about a “defined procedure” to determine the group?
Are Northrup followers responding to a pole an accurate representation?

»If you discard all else there is still one incontrovertible fact that comes from this sample: memory cards DO fail«

Everything will fail eventually. It’s stating the obvious.

»4. If it is possible for a card to spontaneously fail, even if the failure rate is < 1%, then it is madness not to take steps to mitigate the potential loss due to card failure. «

Depends on the real number.
1 in 200 is less than 1%
1 in 1,000,000,000 is also less than 1%
Do you think in both cases it’s “madness not to take steps to mitigate the potential loss due to card failure”?

"Do you think in both cases it’s “madness not to take steps to mitigate the potential loss due to card failure”?"

Yes. I'm also a paraglider and was once a rockclimber. I am risk-averse to a single point of failure.

So a single point of failure with a 1:1,000,000,000 change of failure is a risk you don’t want to take, but paragliding and rock-climbing are ok?

You would lose two monthly mortgage payment.

I lost two cards in three years, no user error, they just stopped working. Data was lost and could not reformat them either. Gone.

Both were from Lexar.

fortunately the Nikons don't use SD cards.

more importantly, polls, in and of themselves, are not scientific. anyone with the faintest grasp on STEM and has viewed a single Northrups video is well aware that facts and science have little to no importance to them.

More comments