The original and the files recorded on the USB disk did not compare: who is to blame, and what to do?

Question

Hard disks

I bought a pair of USB 2.5 "60 GB cheap disks for experiments on Ali from Twochi and Blueendless sellers. The speed is 25 Mb / s. Inside there are IDE disks from different manufacturers ~ 8 years ago. I installed Win 8.1 on one disk, it loaded and worked But somehow I copied a large file (~6 GB) to this disk and then decided to check it with the fc /b command, the Chinese did it anyway. about the same thing happened with another disk.
Questions: Is the disk, disk controller or USB controller on the disk erroneous? And why did it only affect a large file? Where can I buy a SATA to mini IDE adapter and connect via SATA (if that helps)? Will the speed then be greater than via USB 2? I bought such an adapter on Ali, which was more common, but its contacts did not fit the connector on the disk: the step between the needles did not match, the money was returned ...

Answer 1

Show a photo of the disk to Ida with stickers
The problem is obviously that there may be a bad disk
Or its size is not correct
The first one can probably be checked through fschk
The second one can see the size of the disk