I have deleted the file 0002.fff because my disk is full. The benchmark is working on 0001.fff too. It's not need to make the disk full with this chunks. Why did he makes it anyway? Or is there an option?
When f3read reads a sector (i.e. 512 bytes, the unit of communication with the card), f3read can check if the sector was correctly written by f3write, and figure out in which file the sector should be and in which position in that file the sector should be. Thus, if a sector is well formed, or with a few bits flipped, but read in an unexpected position, f3read counts it as overwritten. Slightly changed sectors, are sectors at right position with a fews bits flipped.