The story I am about to retell you starts in China. Some guy finds a really cheap portable 500GB USB hard drive in a store there. He buys one after he has it tested in the shop.
Then he goes home (in Russia) and starts filling it with data. But the drive doesn’t seem to work properly. You upload a movie on it, and you can only play just a few minutes from it. Why?
Here is what the guys at the near repair shop found out.
Instead of proper hard drive platters, the USB hard drive in question had a 128MB flash drive inside that works in loop mode. It writes data until it’s out of memory and then it starts from the beginning replacing the previous records. Add two nuts for proper weight and reprogram the drive’s firmware to report to the computer OS there are actually 500GB on it and you have yourself a fake disk drive.
It fools the user that the files in there are OK. You can see your files on the drive (because the controller writes a false file system), but actually there are just a few bytes of each file.
The conclusion – be careful when you buy cheap Chinese electronics wherever you are.