Test real and fake disks for bad blocks
Unmasking Fake Flash Memory

© Lead Image © Uliya Stankevych, 123RF.com
When it comes to cheap flash memory, buyers should beware. Fake flash memory often offers only a fraction of the advertised storage capacity. With no visible calibration mark, it isn't easy to discover a counterfeit. Here's a test to weed out fake disks.
Any customer in a bar who ordered a pint of beer would definitely complain to the barkeeper if their glass was only a quarter full. This kind of attempted fraud always fails in the real world because of the obvious lack of fluid in the glass, along with the high level of motivation of the consumer and the physical presence of the perpetrator.
Unfortunately, online buyers of flash storage media cannot hope for comparably favorable conditions, although their judgment is unlikely to be impaired by the effects of alcohol. Time and time again, you hear of buyers of USB flash drives and flash cards being duped by shady dealers on the Internet. It is not difficult to find media at surprisingly low prices where the storage capacity is wrongly stated, for example, on eBay [1, 2]. To protect themselves, sellers often make statements such as "the stick will store about 4GB of data."
In this article, I attempt to reveal these counterfeits by running the right tests. As test specimens, I use two Samsung Pro 128GB MicroSDXC memory cards (model MB-MG128) purchased in 2016 from two vendors on eBay.de. If you believe the label, they both should achieve up to 90MB/s read and 80MB/s write performance.
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