Quote:
Originally Posted by ffkip911
fish----ahhhh, gotcha. NDNO is the man, he got me up an running on it.
Now here's a question, spinning hard drives can become "etched" also, when data is stored, the spinning disk sometimes needs to be defraged-----however, i was under the impression that flash has no such drawbacks because there is nothing physically moving. so how could pushing and pulling data from one section wear it out??
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The individual blocks on the SD card have a limited life cycle, like 1000000 writes or something like that. Once those writes are exhausted, they can longer be erased and written to. So if you created a swapfile and that swapfile occupies the same physical area on the card all the times, that area will wear out quickly if linux is constantly swapping inactive RAM data from/to that area. I know we use the SD card to save data / apps / etc, but writing is limited on that (unless you're constantly installing software every second of the day); also, the NAND, card driver under WinMo and Linux is smart because they're designed to do wearleveling; that is, spread out the writes evenly all over the area of the Nand/card so that no one area gets exhausted quickly. On a SD card or NAND, I believe each block contains a header section that tells the OS how many writes have been written to it, so this is how it knows what blocks have been written to more or less; I'm not sure but I believe that's how it works. I believe "reading" is unlimited but if you can no longer write to a worn out SD card, it's useless. So that's why using swapping is not recommended. The advanced features of swapper 2 is nice; you can tell it to delete the swapfile and create a new one each time android boots; when creating the new swapfile, it does at a different area of the Sd card so the previous area is not exhausted out. I believe hard drives have a much longer write life cycle. Any expert, please correct me if I'm wrong on this.
Edit: oops, everyone beats me to the explanation
And mine is inaccurate about the write cycles, I guess it's in the thousands, not millions, which means you can easily wear out that card using swapping.
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03-17-2011, 02:41 PM
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