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While doing some photography reading, i came across some support for archiving photos, videos on SD Cards. The process looked like:

  1. Fill up SD Card with DSLR
  2. Share/publish any choice items via the PC
  3. Physically archive the SD Card

I would contrast this with my own method:

  1. Fill up SD Card with DSLR
  2. Move contents to PC's HDD to free up SD Card
  3. Archive data via traditional PC backup/archive mechanisms

While this makes good sense from a digital photography point of view, I wasn't sure how well it fit for standard PC archival. (This is why i post here instead of the photography stackexchange) Can anyone speak to the negatives of generic PC-based backup/archival via SD card?

  • Is there anything that would limit my ability to retrieve data later?
  • Are there any environmental concerns (moisture, heat, sunlight, etc.) that could cause things to break down?

Edit 1 - in doing some more research, i see that SanDisk has a SD-WORM product that is 100 year archival with (W)rite (O)nce (R)ead (M)any funtionality. What I didn't get was if that was available for purchase or the cost per GB.

Edit 2 - SD-WORM requires special readers/writers, and wouldn't be suitable.

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3 Answers

up vote 5 down vote accepted

I'd say that there are two drawbacks: First, you have no way of knowing what file is archived on which card, so search/retrieval becomes an issue. But the main drawback would be the cost: an external HDD is going to be orders of magnitude cheaper than SD cards.

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Thanks. After your feedback and an online chat with the folks at SanDisk, it seems i can rule out this approach from my consideration. While it is mostly photos that I am worried about, there is enough other stuff to make me cautious. SD rep said there was "no data" as to how long a card might last beyond the obvious 5 year warranty. –  automatonic Mar 7 '11 at 20:04
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NAND flash doesn't hold its charge forever. The electrons trapped in the floating gate slowly leak out. How long it remain readable depends on the density of the flash. The 3xnm flash found in most SD cards today has a retention time of around 5 years. The 2xnm flash that is starting to show up now has a retention time a bit lower than that. How much lower I don't not know exactly. 4 years or something like that I supect.

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+1 for mentioning data retention. People often confuse amount of time during which card can be used and amount of time during which data can be stored on a card. –  AndrejaKo Mar 7 '11 at 20:27
    
+1 for another good consideration and distinction. Much appreciated. –  automatonic Mar 8 '11 at 18:02
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Not to beat a dead horse, but two other downsides that jump to mind:

-not being able to easily determine if the data was "changing" on the cards (e.g. if you've got things relatively centralized on a hard drive, you could easily do something like occasional MD5 checksum checks)

-much more difficult to do regular offsite backups (a fire or theft could easily cause a problem long before bit rot)

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+1 Also interesting considerations. Thanks! –  automatonic Mar 9 '11 at 13:20
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