Good day...This probably one of the last long article I will put here.
There was a debate on the lifespan on other forum and the following was a direct reply:
technicsplayer wrote:
> you underestimate specs, san disk is 41 years for 20 formats a day
> - for ultra 2 it would be 274 years. These are MINIMUM specs.
> most users will be dead before their cards wear out through write
> cycles
The figures does not stand because the test condition is not stated, most important being the card size used.
I have put up the following reply as my initial posting did not cover in sufficient detail. So sit back and enjoy...
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ALL the flash card (SD, CF, XD, etc) makers could have their own propietary memory controllers. But they get their memory core, the NAND flash memory, almost from one of the 3 large NAND memeory makers I mentioned previously. They can monopolise because they could do it economically and superior technology. The card makers could even be using memory controllers from them, thus relegating themselves to OEM of sorts. But they will not tell you. Unless you are generous enough to buy cards and cut open them to satisfy your curiosity.
I personally have been using Toshiba and Samasung NAND flash memory chips and it is clear from their technical documents its write-cycle is 100K typical.
The lifespan calculation I put for 20 times a day is as follow:
100000/365/20 = 13.7years. Operation = re-format and take afew pictures, then repeat the cycle.
This is valid because of re-formating which cause the initial part of the memory arrary to be re-written 20 times a day. The memory cell there will fail after 13.7 years. This is regardless of card capacity.
But if you do not re-format, your card could last much longer. Assume you have a 1GB card. If you continue to fill the cards with pictures, each picture about 2MB size, to fill up each card =500 times without sequential shooting. After that you reformat to 'flush' the content since it is easier than 'Erase ALL' and less harmful. This means shooting 500 times will reduce the 100K write cycle by 1 only since only then the same memory cell will be accessed.
In that case, your 1GB card can be used for 13.7years x500= almost infinity.
By the same token, your card will last shorter if you use sequential shooting because each card will take less than 500 times to fill up, with same condition.
With regard to Sandisk Ultra 2, or 3 for that matter, lasting 6 times longer than regular Sandisk, it is utterly un-believable. Sandisk regular or Ultra 2 both uses NAND flash chips only with different speed rating but their technology is the same. Only that Ultra 2 has better environmental protection for it to have more dynamic climatic and rough usage. Speed has nothing to do with lifespan.
My explnation is solely based on technical understnding and not hearsay or rumour. Of course I will be more than happy if somebody could prove me wrong by furbishing some technical documents from some reliable source other than aunty advices from some sites.
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