> The problem is that disks are confirming writes before they actually store the write in the non volatile target.

Consumer NVMe's are bad about this. They'll fill a write buffer on the drive and flush it when it is convenient for the device, regardless of what the OS wants.

The Samsung 963 NVMe is an interesting device though because it has little capacitors on it that will flush the contents of that buffer when power is suddenly lost. But it still also just fills that write buffer and does not commit to disk when it said it did.

This is how they are gaming the benchmark tests.