Re: Fragmented? 75% full?
These things can only write blocks, and when they run out of free blocks they go to another mode. They find a block with free pages and read that block into cache (reads are faster than writes). They then erase the block (erase is veeeery slow compared to read or write), add the new data to the cache, and then write cache back to the block.
Of course, a disk with a lot of free time will not be so much affected as there is more time for garbage collection. TRIM helps, but is imperfect.
