I'm trying to figure out what's going on. I've got a Mac Pro connected with a Sonnet Twin 10G adapter to a Windows 10 PC with a StarTech 10G PCI card. If I try and transfer a file, I get about 350MB/sec. If I do an iperf test (and set the TCP window really high), I get much higher:
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-1.00 sec 1.11 GBytes 9.50 Gbits/sec
[ 5] 1.00-2.00 sec 1.15 GBytes 9.88 Gbits/sec
[ 5] 2.00-3.00 sec 1.15 GBytes 9.89 Gbits/sec
[ 5] 3.00-4.00 sec 1.15 GBytes 9.89 Gbits/sec
[ 5] 4.00-5.00 sec 1.15 GBytes 9.89 Gbits/sec
[ 5] 5.00-6.00 sec 1.15 GBytes 9.88 Gbits/sec
[ 5] 6.00-7.00 sec 1.15 GBytes 9.89 Gbits/sec
[ 5] 7.00-8.00 sec 1.15 GBytes 9.88 Gbits/sec
[ 5] 7.00-8.00 sec 1.15 GBytes 9.88 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-8.00 sec 0.00 Bytes 0.00 bits/sec sender
[ 5] 0.00-8.00 sec 9.73 GBytes 10.4 Gbits/sec receiver
I've turned on Jumbo Frames and set the MTU to 9000 on both devices. No matter what I do I can't get over 350MB/sec on a file transfer. I'm trying to get this above 700MB so I can stream 4K video to my editing software.
Any other suggestions? From my tests, it looks like the connection is capable of 10G but for some reason something in macOS Sierra or Windows 10 is limiting the speed.
