Gigabit Ethernet getting less then 50% throughput on file transfers

Question

I am trying to copy about 180 GB worth of files from a dell 6450 (server 2000) with a gigabit ethernet card to a 2850 (also gigabit, server 2003) Since it was gigabit i figured the copy could be done in one night after hours. but when i started the copy it only ran at 10-15% capacity (according to the 2850's task manager).    I tried running directly from one box to the other using a cat6 crossover cable... and with a gigabit switch, same result. then i tried a speed test from one 2850 to another using a crossover and it toped out at 50% capacity using windows file sharing and around 20% with ftp(filezilla).   I looked at the microsoft knowledge base it said you could change the network buffer size, for server 2000 but didnt offer anything for server 2003. Any ideas?   thanks,   Goober

mombodog · Answer

Gigabit unfortunately is for many computers to connect to 1 server, not 1 to 1 with gigabit performance, What I do understand is that to get the near performance people expect when they use Gigabit 1 to 1 is that the gigabit network adapters must support what is called 'Jumbo Frame' (Increasing the MTU above 1500) technology and must be configured properly at each end to see a  performance gain 1 to1.   Remember that 100 mbit lan cards only would give you 50% of the bandwidth 1 to 1, so you really get 50mbit from 1 pc to another on a direct copy, it reserves the other 50% for other pcs on the network even though there are none.   So yes I expected gigabit to do the same 50%=500mbit throughput,  Unfortunately it was designed for large networks not 1 to1 performance, but like I said you can get increased performance with Jumbo Frame Technology.   http://sd.wareonearth.com/~phil/jumbo.html    what is jumbo frame   http://www.theinquirer.net/default.aspx?article=32760             interesting article. Message Edited by mombodog on 11-08-2006 05:32 PM

NemesisDB · Answer

while jumbo frames will improve throughput by a small amount, their main purpose is to reduce CPU load -- so unless you're CPU limited I wouldn't expect jumbos to help *that* much.

you can look into optimizing your tcp window settings, and lots of websites will offer different advice there. In the driver properties, make sure offload TCP large send and Offload check sum (both ways) are enabled.

Disable the ICS/Windows firewall service: http://support.microsoft.com/kb/842264

50% throughput out of 1000mbps is frankly very, very good in my experiance. I'm amazed your HD can even sustain a 60+MB/second transfer rate...

Networking, Internet, & Bluetooth

Gigabit Ethernet getting less then 50% throughput on file transfers

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