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I want to install Archlinux on a microsd card (I want to dual boot a Windows 8 intel tablet). My question is if there is wear levelling implemented on this like a usual SSD disk? I have not found a definitive answer on Google. If yes, I assume, I would use an ext4 filesystem like an ordinary SSD disk otherwise maybe F2FS?
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[Disclaimer: I'm not too knowledgeable in this field, just throwing in what I know...]
AFAIK MicroSD cards don't have wear levelling. In the case of the SSD the levelling is handled by the SSD's onboard controller (though I heard newer models can disable this and delegate this to the OS), so really a wear levelling solution would have to be in software if you really wanted it.
That said, wear levelling also requires some spare blocks on the flash storage in the event that a possible failure is detected (though again, not sure how you would detect this on an SD card), so you'd probably loose some capacity.
Finally, I would recommend F2FS over ext3/4, if only to spare the SD card from all those journal writes (I can't vouch for the quality of cheaper ones >.<).
Another thing to consider when choosing a file system is that SD cards actually have much larger block sizes than the logical "sector" size (typically 512 byes) - So if you overwrite a logical block, and then the next, and so on one at a time, the SD card will repeatedly erase the same physical block and re-write it with the single logical block changed.
Write caching can go someway to alleviate this (unless you get that dreaded "caching mode page not present" when you insert the SD card) but not always.
F2FS would be better in this case because (IIRC) it has this design "feature" in mind when it writes stuff to those kinds of media.
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http://electronics.stackexchange.com/qu … controller
http://wiki.laptop.org/go/NAND_Testing
http://us.hardware.info/reviews/4544/4/ … t-sd-cards
http://forums.sandisk.com/t5/Mobile-mem … d-p/292873
The answers seems to be: it depends. More expensive cards have some wear leveling, but whether it's just marketing bluff or it's real, you'd have to test.
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