The issue is TCP's congestion control needs to wait for an ack before sending the next packet so the latency kills throughput.
Changing to UDP would get rid of the congestion control but UDP on its own would have congestion issues killing its throughput.
Bittorrent created their own congestion control called ledbat and then added that onto UDP to create UTP which could help. There is also UDT which has its own congestion control algorithm designed for 10gbps+ connections, which would significantly fix the issue.
I would argue that drbd is the right thing 24x7 or zfs send. The problem with kind of bittorrent is, you have to retransfer the whole block and not just the packet, but could work too, interesting.
