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landev 10-23-2006 12:45 PM

NIC transfer speed fast... receive speed slow
File transfers from a Fedora 4 box to Fedora 4 servers are running at speeds of 44.5MB/sec. When I try to go the opposite way (from servers to workstation) my transfers are running at 4MB/sec. Auto negotiation is turned on and reporting 1000FD. I don't see any errors. Anybody got any ideas on this one?


pats 10-23-2006 04:50 PM

are they both stock installs?

sounds like it could be a transmit/ recive buffer problem at one end.

is the hardware the same at both ends? it may be that one of the NICs is a bit shitty. If you have spares of the same brand try doing a more scientific test.

also it could be poor bus handling by one end of the transfer.

landev 10-30-2006 04:39 PM

The OS load was done by Penquin. There are on-board NICs on the servers and the workstation. I hard coded the connection speed at the switch to 1000Mb/auto negotiate and tweaked the sysctl.conf file and got the incoming files up to 24 MB/s (outgoing is still 44.5MB/s. Penguin suggested installing the latest NVidia chipset drivers... that only slowed things back down (though not as slow as before) to 14MB/s. I'm becomming suspicious of the hardware (eth0 on the workstation died shortly after we received the system, so it's been running on eth1.) Hmmm...

pats 10-30-2006 05:23 PM

sounds like some busted hardware to me.. i'd try it with another system if you can. possibly return the hardware if you can?

a good tool for testing max bandwidth capabilities is 'iperf', that'll at least tell you if its a software problem with either the client or server or if its a hardware problem. i doubt its gonna be a kernel tcp problem seeing as they're all running the same build i guess? just stock FC4?

pats 10-31-2006 07:58 AM

might be of some use to you as well.

landev 11-07-2006 03:09 PM

Well, at this point I am on hold with Penguin. They sent a script to produce some meaningful output diagnose the problem. Haven't heard back but will give it until the end of the week. Thanks for the link... nice one to add to my collection. I'll keep you posted...

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