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Fake Flash Memory

November 10, 2015

Recently, I was advising someone that the simplest way for me to transfer around 200GB of data to them was on a large SD card or microSD card.  Boy, was I in for a surprise.

First off, if you are looking at an advertisement for a 256GB microSD card you will be disappointed.  There simply are none.  Well, none that actually have 256GB of storage capacity.  If you look at Amazon (as I did) you will discover there are both pretty expensive cards and some that are incredibly cheap.  Surprise!  The incredibly cheap ones have only a little memory in actuality and have a hacked controller that pretends there is much more storage available than there actually is.

How this works is simple.  You have a card with 2GB of actual storage on it but the controller “pretends” to allow accessing 256GB by simply writing to the same 2GB that is there over and over again.  Now, the way computers and file systems work, you are actually writing information to the directory constantly as you are writing files, so the directory is going to be written out last almost always.  The file data, what there is of it, is going to suffer because of this.  But the way this works allows you to think you have written far more than 2GB of data to the device and when you check the directory it appears to all be there just fine.

When you go to read it you will discover that some of the files have been corrupted.  In fact, everything except for the last 2GB or so will have been corrupted and the directory will likely have corrupted some of that as well.  You can get a sense of this by looking at the listings on Amazon with the customer reviews.  Some customers seem to be happy and these have to be reviews put there by the folks selling these things.  Everyone else is pretty unhappy with their purchase.

Right now, there is a reasonable test program for determining if your USB flash drive has a faked capacity and you can download it from this site.  This requires an empty drive for testing, so if you have anything you believe might be good on it, copy it first.  It is recommended by the author that you quick-format the drive before starting so as to remove any hidden folders or saved “trash” if you have used the drive on a Macintosh computer.

So what do you do if you bought a cheap USB drive or memory card and discover the capacity is faked?  Well, I am pretty sure most people aren’t on the phone to their retailer complaining about it.  In most cases, the retailer will disclaim any responsibility saying they bring a product in and sell it; if the product doesn’t work you can get a refund, minus shipping cost.  Well, if you have a card less than $10 the shipping cost is going to eat up a good part of that return, so you figure why bother?

The result of this is (a) nobody returns them or so few do as to be negligible, and (b) the retailer is uninterested in the quality of the product even if you do return it.  So what do you think should be done about these flash drives and cards?

I think it might be reasonable to develop a testing tool that does not require the drive to be empty in order to be used and can report on some meaningful statistics about the drive as well.  When this is done, if it happens, it will be listed on the consumer software page on the InfinaDyne web site.

If you have a fake flash drive or card I would be very interested in obtaining it for testing purposes.  Click for our address.  If you send me a card, include your email address and I will see that you get a free product from InfinaDyne for your trouble.  I was thinking about buying one intentionally, but this seemed to be rewarding the scammers that make these things.

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