Anyone with clues on gigabit network tuning?

mnet674

mnet674

mnet674

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Cambridgeshire
Hi folks, planning on getting a fileserver setup and have GbE interfaces in my pc and the server box with a nice switch and Cat 6 running the whopping 2 feet between the boxes...

The problem is while I can offload data from the PC to the server box at a good 650-700Mbps (which right now is about the disk write speed), attempting to transfer back results in a speed of 200-300Mbps, which I guess isn't terrible but is still fairly annoying compared with the other direction ;)

I've spent half the weekend mucking about with tcp windows sizes, mtus and registry hacks, tried using both the nvidia and realtek ports on my pc and the results are still the same...ludicrous speed in one direction and almost exactly a half ludicrous speed in the other :confused:

Any ideas?
 
This is probably a limitation of the gigabit interfaces on your PCs. The motherboard implementations are not pure hardware like an additional card would be and use the CPU to do much of the work. Around a quarter of the maximum theoretical throughput is quite normal.
 
im guessing the other half of the equation is the disks

im guessing the server can write faster than your consumer disk in your PC ?
 
Snapshot said:
This is probably a limitation of the gigabit interfaces on your PCs. The motherboard implementations are not pure hardware like an additional card would be and use the CPU to do much of the work. Around a quarter of the maximum theoretical throughput is quite normal.
Click to expand...

After some further testing I reckon you've hit the nail on the head here, el cheapo branded devices are hitting their maximum throughput! On the other hand even 25MB/s is a nice improvement over the previous 100Mbps connection so I'll just live with it ;)
 
Is the server actually a server or something youve knocked up?

You are highly unlikely to see significant transfers speeds between servers and client devices, betweens server yes but it is dependant of hardware such as Raid levels, network teaming, TCP offloading, Frame sizes etc etc

You can also take into account the forwarding rate of the switch and the method in use for switching packets, "store and forward" "Cut Through" and "Fragment" free. using Jumbo frames can also helps in certain cases but is dependant on both client and switch hardware capabilities.
 
Just run iperf in both directions, if it comes back with similar values each way then the nework is fine and your PC is the issue. (iperf is disk independent so justs tests the network).

I'd expect cheap home gigabit kit to top out at 700mbps at most, 300 is too low though, even netgear kit should go beyond that...
 
What software are you using to transfer?

I found that certain FTP clients/servers held back my gigabit at home. Once I changed I went from ~30MB/sec up to ~60MB/sec.
 
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