Not Getting Expected Network Throughput - Why?

From We Got Served Wiki

There have been many posts on the We Got Served (WGS) forums from folks who have installed gigabit networks but have been disappointed in the throughput results. There could be many reasons for poor network performance and there have been different solutions proposed including enabling jumbo frames (not recommended). However, before looking at solutions it might be a good idea to establish realistic expectations.

The theoretical throughput for a gigabit network is 1000 megaBITS per second or 125 megaBYTES per second. However, the speed at which a file can be transferred from client to server or server to client is only partly determined by the speed of the network. It is also affected by how fast the information can be read from the source disk and can be written to the destination disk. There is an excellent article which does a great job of explaining this. What it shows is that with a Gigabit network the file transfer rate is almost totally determined by disk performance rather than network speed.

The message here is that beyond a certain point, increasing network speed will not increase end-to-end file transfer throughput because the network is not the limiting factor. Where that point is depends primarily on the read/write speed of the disks. So, assuming a healthy gigabit network, the way to increase file transfer speed is to to get faster disks.