I once heard it suggested that using multiple smaller memory cards was a good way to decrease the chances of losing data. It's hard to argue with the logic that several memory cards are unlikely to fail all at once but reality is complicated and there could be reasons that this advice is either unimportant or maybe even harmful. How does this pan out in reality?

Is the rate of failure of major brand memory cards high enough for this to be a realistic concern?

Handling a larger number of small memory cards could increase the chances for human error. Am I likely to come out ahead with smaller memory cards?

  • \$\begingroup\$ Failures due to accidental damage are probably most likely in anything better than utter junk, though loss is likely to be more significant still. \$\endgroup\$
    – Chris H
    Commented Apr 10, 2016 at 11:22
  • \$\begingroup\$ And photo.stackexchange.com/a/39043/15871 \$\endgroup\$
    – Michael C
    Commented Apr 10, 2016 at 11:33
  • \$\begingroup\$ The core reason for card failure is user error - removing it from windows without properly ejecting, dropping in the dirt, wet/oily fingers, or such. If you treat them correctly, they very rarely fail. \$\endgroup\$
    – Aganju
    Commented Apr 10, 2016 at 13:07

2 Answers 2


Smaller memory card requires switching cards more often, which can be a limitation. The SanDisk CompactFlash Memory Card Product Manual (available SanDisk CompactFlash Memory Card Product Manualhere : ) gives the following specifications :

  • MTBF > 1,000,000 hours (MTBF=Mean Time Between Failure)
  • Minimum 10,000 insertions

So if you are a "regular" photographer, given the hypothesis that you will fill one card per day and then switch to an other, then insertions specifications should limit you to 10,000 days, so more than 27 years.

Now if you only take into consideration the MTBF, and 10 hours of shooting per day, your CF card is expected to last about 100,000 days, more than 270 years.

Many more factors should be taken into account to give a correct conclusion, such as read/write pattern, temperature, humidity or card technology. So, sure, when a card fails, you may lose a many data as the card can contain, but the probability of that can't probably be accurately measured.

I don't think that memory card capacity is the problem regarding losing data. It probably has more to do with how you take care of your cards.

  • 1
    \$\begingroup\$ The cliffhanger is killing me. What happens if I'm a regular photographer? \$\endgroup\$ Commented Apr 10, 2016 at 10:37
  • \$\begingroup\$ yep, my second edit went AWOL. Corrected :) \$\endgroup\$
    – Olivier
    Commented Apr 10, 2016 at 10:40
  • \$\begingroup\$ Statistics can bite you easily - unfortunately... MTBF means, unfortunately, very little. A card with MTBF > 1.000.000 can fail after one hour and a card with a MTBF > 10 can live 1.000.000 hours. All it means that in (accelerated testing) the cards last more than 1.000.000 hours on average. There will be outliers either way - with a greater and shorter lifetime. There is also th eoption of a not up to spec camera applying more potential etc. increasing wear/risk of failure too. \$\endgroup\$
    – DetlevCM
    Commented Apr 10, 2016 at 11:58
  • 1
    \$\begingroup\$ I completely agree with you @DetlevCM. MTBF is far from being accurate. In aeronautics and lot of other fields, when electronics are concerned, fiability is always given for a specific life cycle. To much to ask for a question about personal use... \$\endgroup\$
    – Olivier
    Commented Apr 10, 2016 at 12:12
  • \$\begingroup\$ Based on a simple reliability distribution such as an exponential distribution, with a MTBF of 1,000,000, you can expect 1 out of 1,000,000 cards to fail in the first hour of use. After 250 hours of use (one hour per day, every week day of the year), 249 cards have failed. \$\endgroup\$
    – crunch
    Commented Apr 12, 2016 at 9:14

There may not be a definitive answer.

Some arguments for using fewer, larger cards:

  • Less card swapping. When using small cards, you could potentially miss the shot because you have to swap cards.
  • Lower chance of user error. If you have a dozen cards then keeping track of formatted cards, used cards, backed-up cards... is a disaster waiting to happen.

And for more, smaller cards:

  • If you swap cards frequently, losing a single card due to loss/theft/failure is a lower total loss as a percent of all photos.

As mentioned by @Olivier, failure is a low probability event, but the flip-side is that failure is a high impact event! Note that manufacturer lifetime estimates are based on a large sample; an individual card could fail after one more use, and you'd have no way of knowing beforehand. If you only have one card with you, that could be a catastrophic failure (for you). We've all heard stories of even good quality cards failing while still new.

Theft/loss is a tricky one. If someone steals all your gear, then the number of cards makes no difference. However, if someone steals all your gear that you have on you at that point in time, and the bulk of your cards are safely locked in your hotel room, then you minimise your loss. Other examples could be if you fall off a boat and your gear floats away/sinks - same argument.

My approach: I have multiple big cards. Big enough that I won't run out mid-shoot. And enough cards that I can change as often as required, and leave the used cards safely locked away somewhere.

  • \$\begingroup\$ I'm the small card camp but a downside of this method is that the most likely time to lose a card is when you swap them, and loss is the most likely failure mode (I think). I would never use a card for longer than a day on a trip though. And I use a backup hardrive with a battery and card reader built in. \$\endgroup\$
    – Chris H
    Commented Apr 10, 2016 at 11:21
  • \$\begingroup\$ I tend to change cards in the evening after a day's shoot. My next purchase goal is a backup hard drive with card reader. I've been caught out before not having space on a card during a day, so upgraded to all 32GB cards - even using RAW I can get over 1,000 photos on a card. \$\endgroup\$
    – crunch
    Commented Apr 12, 2016 at 8:59
  • \$\begingroup\$ mine is a few years old so wouldn't be all that useful in your case, but I deliberately went for a basic (cheap) model as the canon-branded ones only did SD and CF cards, and only filetypes that canon knew about. mine is filetype agnostic so I can back up my video camera, a samsung camera's raw files etc. \$\endgroup\$
    – Chris H
    Commented Apr 12, 2016 at 9:21

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