Hi Ed, There's some good information here: https://www.blackhat.com/docs/us-14/materials/us-14-Oh-Reverse-Engineering-Flash-Memory-For-Fun-And-Benefit-WP.pdf
Basically though, USB drives are cheap, and they're frequently disconnected from power for extended periods of time, plus the flash controllers in them are very, very dumb. None of the extra work that the controller performs in a flash drive happens in a USB drive. The cells aren't likely to get degraded by excessive wear, but any particular bit of data is likely to lose charge because the shelf life is limited (especially on cells as cheap as the ones they throw in USB flash drives). --Matt On Tue, Nov 17, 2015 at 10:58 AM, Edward Ned Harvey (lopser) < lop...@nedharvey.com> wrote: > In regular hard drives and SSD's, they have FEC chips or equivalent > (forward error correction) so whenever the platters return a bit error, > that error should be noticed and the corrupt data should not reach the OS. > > > > I have seen many times, USB and SD cards start silently returning corrupt > data. You waste a bunch of time figuring out where corrupt data is coming > from, and then discover that if you literally read the same file from the > USB drive more than once, it comes out differently. So you throw out the > USB drive, and wish you could get your data back. (And the last several > hours you spent debugging). > > > > The usual filesystems that you use on USB drives don't have data integrity > built-in, and that's not going to change anytime soon, so I am hoping to > find some kind of higher quality USB flash drives, that actually provide > data integrity, such as ECC ram does, but I haven't found a good search > term yet. Any suggestions? > > > > I've tried USB Flash Drive Error Correction, error detection, fec, ecc, > data integrity... > > > > So far all I've found is this (found by searching for USB Flash Drive ECC): > > http://eflash.apacerus.com/spec/USB/Drive/Industrial-USB3.0_EH353.pdf > > They have a whitepaper indicating ECC and EDC. > > > > When I search for those, they're not sold at the usual vendors like > amazon, newegg, bestbuy. They're sold by mouser, digikey, etc. They're > called "industrial." And honestly, the prices are not crazy. So I'm > probably buying some of these today, but I'm trying to learn something > here, and figure out how I can consistently find good drives in the future. > > > > Anyone know anything? > > _______________________________________________ > Tech mailing list > Tech@lists.lopsa.org > https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech > This list provided by the League of Professional System Administrators > http://lopsa.org/ > >
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