Flash Memory: Caveat Emptor

We all love new tech. Some of us love getting the bleeding edge, barely-on-the-market devices and some enjoy getting tech thirty years after the fact to revel in nostalgia. The similarity is that we assume we know what we’re buying and only the latter category expects used parts. But, what if the prior category is getting used parts in a new case? The University of Alabama in Huntsville has a tool for protecting us from unscrupulous manufacturers installing old flash memory.

Flash memory usually lasts longer than the devices where it is installed, so there is a market for used chips which are still “good enough” to pass for new. Of course, this is highly unethical. You would not expect to find a used transmission in your brand new car so why should your brand new tablet contain someone’s discarded memory?

The principles of flash memory are well explained by comparing them to an ordinary transistor, of which we are happy to educate you. Wear-and-tear on flash memory starts right away and the erase time gets longer and longer. By measuring how long it takes to erase, it is possible to accurately determine the age of chip in question.

Pushing the limits of flash memory’s life-span can tell a lot about how to avoid operation disruption or you can build a flash drive from parts you know are used.

29 thoughts on “Flash Memory: Caveat Emptor

    1. Some devices use actual SD cards for their memory, in which case you could take apart the tablet and swap out the card if you suspected it was re-used. I found a 2GB SD card inside my e-reader after it broke acting as the main storage for the device.

  1. Unfortunately the EEE Spectrum article linked is light in details, and only points to a paywalled conference as a source. I would be curious to know if their tool is openly available, and how it compares the erase times : database of known good chips maybe ? If you have to remove the chip from the board to test it, it will remain out of reach of 99% of the customers actually scammed by such chips.

  2. I wonder if that might be why the dirt cheap ZTE smartphones I got for mining didn’t last long? Granted, that’s a very heavy use case and having it break down at 6 months or so is not surprising. (That was when such an investment would break even in 1-2 weeks and thus low risk.) But all 3 of my Moto Es have outlasted 4 ZTEs doing more or less the same thing.

    1. Do you happen to have any documentation on this? I mean mining on phones sounds interesting. I know these days it doesn’t make any sense but doesn’t change the fact that it’s interesting.

      1. Probably he does not mean mining crypto currency (I don’t see how that can be more profitable than more powerful hardware) but phone mining. This is building a farm of phone to run apps that pay you the view add. This used to be very very profitable.

  3. I don’t know what their problem was, but I bought a lot of four ADATA UV128 16 gig USB 3.1 flash drives from Newegg. Their write speeds were abysmal, barely hitting 9 MB/Sec. All four have died, same failure mode, acting as though they’re constantly being plugged in and removed.

    Fortunately ADATA has a lifetime replacement warranty on their flash drives. The replacements hit 17 MB/Sec write speed. Still slow for USB 3 but faster than most of the USB 2 drives.

    I still have the 4th dead drive. If someone wants to have a look to see what happened, I’ll swap it for a good 16 gig USB 3 drive.

  4. Perhaps legislation to to be created that requires the label that a product contain recycled or refurbish component should be unmistakably labeled as such. Allowing a consumer to decide if they want to spend more for all virgin parts, or take the gamble of saving money with recycled and reburbed units. As things stand in the US no the consumers have no recourse.
    Perhaps hackaday covered it and I missed, but I found this at the IEEE interesting. Not only does agovernment agency exercise common sense in regards to the abusing the DMCA. The motor vehicle manufactures have decided to act reasonably.

    1. who is in charge of defining what the phrase “virgin parts” means? And what does it actually mean, anyway? Who will adjudicate disputes over the meaning of this phrase? If we throw these virgin parts into Halemaumau, will the lava fiisures subside?

    2. Regulation! Solving everything from genuine counterfeit Chinese parts to gun killings.

      Buying from reputable manufacturers via reputable retailers is generally the answer.

  5. The simile is not very well chosen. Although you’d probably not get an used transmission in your new car, you will most likely get a refurbished part if you get an replacement gearbox when it is repaired. Same for engines and other parts like AC compressors.
    There is a reason why you pay a deposit when ordering a replacement engine, you get the money back when you return the old block.
    And, anyways, what’s it to you? You pay for the functionality and the quality. As long as the parts work, I see no reason to complain. The problem with re-used memory is the lack of quality and are legal problems as the memory is not thoroughly erased.

    1. fair enough. I am cool with used parts as long as I am told that they are used and have been reasonably assured that they are not worn out (excepting of course parts where safety is really important like life support ect.)

    2. In case of the transmissions, it may even be better, as the used gears and other moving parts that pass the inspections were run in together, you couldn’t achieve this level of fit on virgin parts even if wanted to (at least not for any sensible amount of money) ;-)

      However flash memory can’t be refurbished, it just keeps degrading with use…if it was labeled as used and cheaper then new – fine, let the free market choose.

  6. After getting burned getting fake flash even from reputable dealers, I now buy my flash directly from mfg factory stores. I flat refuse to ever again buy ANY flash memory from ANY Chinese source. I run several of the fake flash detectors, especially on brand new chips. Factory stores is the only way to insure you won’t get a fake.

      1. I fear MAYBE not… The dozen 64GB sticks I bought off Aliexpress for $8 each certainly weren’t. Actually contained 8GB chip each, configued to wrap around on itself. So you not only lost writes beyond the 8GB actual size it also trashed anything written to the first 8GB.

        Got my money back as well as got to keep sticks. I reformat them to actual size and then use them as givaways. But even though ruled against by Aliexpress the seller was still selling the same bad sticks last time I looked.

  7. We buy blister packed USB drives for our products directly from Kingston (DataTraveller series) and find them as variable as drives bought through ebay. (Except that the ones from Sandisk always have the advertised storage :) )
    Data transfer speeds can vary by an order of magnitude. Where as SD Cards have a clear speed rating driven by the digital products they’re installed into like cameras and whatnot, USB seems to be “you get what you get”.
    If the USB drive industry had started labelling with speed of transfer rather than interface speed (USB 2.0) as a selling point rather than just storage speed I think the world of storage as a whole would be better off.

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