NAND loses its charge?

M

munkle

[H]F Junkie
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Jan 16, 2005
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So I was reading this review. It was talking about write cycles and how if you wrote 7gb a day your nand would lose it's charge after 10 years before you got through the nand write cycles.

I don't get it, so after a certain amount of time nand is useless and you loose your data on it?
 
Yes, it can lose charge. It's not a very good long term storage medium. The more you use a cell the poorer it's data retention is.
 
So what is a good long term storage medium? I have a bunch of photos that I just leave on sd cards, but now I am going to move them somewhere else.
 
The flash in SSDs should conform to JEDEC JESD47F specification. This was discussed in detail in this thread:

http://hardforum.com/showthread.php?t=1502663

Bottom line is that the flash chips should maintain their data for at least 1 year when the SSD has reached its maximum cycle count (5000 for 34nm MLC), and 10 years when it is new. Between 10% and 100% of max cycles, you can interpolate the data retention time as roughly 1yr / (fraction of max cycles). So, at 1000 cycles, you can expect a data retention of at least 1yr / (1000/5000) = 5 years.
 
munkle said:
So what is a good long term storage medium? I have a bunch of photos that I just leave on sd cards, but now I am going to move them somewhere else.
Click to expand...
Well, I guess it depends on what you mean by "long term". I'm thinking 10+ years. I'd probably use high quality optical media and a real spinning HD with yearly checks for data integrity of each.
 
munkle said:
So what is a good long term storage medium? I have a bunch of photos that I just leave on sd cards, but now I am going to move them somewhere else.
Click to expand...

Tape, blurays, or possibly an unpowered HDD but I would not count on an HDD spinning up after 10 years on the shelf.
 
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