When u read a file for the first time, windows keeps it cached in ram. When u read it again, it comes from the cache. On my system, i can read a 100MB cached file at about 1 GB/s.
When u want to test the maximum throughput of ioFTPD, u don't use harddisks, because those are the slowest component. U transfer a cached file, then the limit is 1 GB/s.
The client in this case, doesn't write the file to the harddisk, it just downloads it and then discards it.
ftp.exe: get file > nul
The speed of the NIC is unimportant here, because the tests are local transfers. Localhost -> localhost doesn't go through any network adaptor. (This way, u can develop and test networking applictions without being connected to a network). The speeds darkone got were most likely 253 MB/s and not 253 Mbit/s.
Please correct me if i'm mistaken