Network cards and achieved throughput

Dr. Z · 07-03-2007, 23:42

Here at uni I run a little network and I have a few little niggles that keep cropping up that I think can be put down to my network cards but I am not sure.

Omitting all of the AD, DNS, DHCP, Level 2 management and all that stuff, basically I have a windows-based server box which has a few shares that are accessible from any of 10 client PCs. At any one time, the server has a load of around 300kbps but at "busy" times this can sit at 1-2mbps for sustained periods - all of this is no problem at all.

The real problem comes whenever peak/burst speeds are required (biggish data transfers). I expected my gigabit lan to have a sustained throughput of somewhere in the region of 30-40mpbs worst case (my drives can sustain high 70s/low 80s individually but I have a striped set array and a mirror in operation). However, I only actually get peaks of around 18mpbs and a sustained average of closer to 13-14mpbs.

I have tried a lot of things, including moving to a (well configured) linux/samba based configuration but it just doesnt seem to make much difference - is this down to my network cards? In the server machine I have a pair of D-Link DGE-530Ts which I expected to run fine. I swapped one of these with a Netgear GA-311 to no noticeable difference.

I am at the end of my list of things it could be. I dont really want to splash out on something like an Intel Pro/1000 for each of my machines that needs the throughput because it will mount up!

What cards are a good tradeoff between actual throughput and cost? Have I missed a setting or something that is causing a bottleneck? I am using a Netgear 8-port gigabit switch and although removing it didnt make any difference could it have its own small part to play? I dont know, I am totally lost as to why everything is so slow!

07-03-2007, 23:42	#1
Dr. Z I'm going for a scuttle... Join Date: Jul 2006 Posts: 2,021	Network cards and achieved throughput Here at uni I run a little network and I have a few little niggles that keep cropping up that I think can be put down to my network cards but I am not sure. Omitting all of the AD, DNS, DHCP, Level 2 management and all that stuff, basically I have a windows-based server box which has a few shares that are accessible from any of 10 client PCs. At any one time, the server has a load of around 300kbps but at "busy" times this can sit at 1-2mbps for sustained periods - all of this is no problem at all. The real problem comes whenever peak/burst speeds are required (biggish data transfers). I expected my gigabit lan to have a sustained throughput of somewhere in the region of 30-40mpbs worst case (my drives can sustain high 70s/low 80s individually but I have a striped set array and a mirror in operation). However, I only actually get peaks of around 18mpbs and a sustained average of closer to 13-14mpbs. I have tried a lot of things, including moving to a (well configured) linux/samba based configuration but it just doesnt seem to make much difference - is this down to my network cards? In the server machine I have a pair of D-Link DGE-530Ts which I expected to run fine. I swapped one of these with a Netgear GA-311 to no noticeable difference. I am at the end of my list of things it could be. I dont really want to splash out on something like an Intel Pro/1000 for each of my machines that needs the throughput because it will mount up! What cards are a good tradeoff between actual throughput and cost? Have I missed a setting or something that is causing a bottleneck? I am using a Netgear 8-port gigabit switch and although removing it didnt make any difference could it have its own small part to play? I dont know, I am totally lost as to why everything is so slow! __________________