Dual GB NIC Linux box between 2 NT boxes

[Aastrill]

How can I have a linux machine act as a 'middle-man' between two NT 4.0 servers?

The linux box has 2 NIC's, and each NT box has 1 NIC - all of which are identical fiber-based gigabit ehternet cards: eth1 is directly connected to NT box #1, and eth2 is directly connected to NT box #2.

My goal is to initiate a copy from the linux box that will copy a large (4+ GB) file from NT box #1 directly to NT box #2, without writing to the linux disk(s).

NT to NT copying doesn't utilize the GB NIC's anywhere near their capacity, so I was wondering if a linux box in the middle performing the actual copy would get better performance.

If there are any tweaks I should perform to boost the performance of the NIC's, that would be great information as well!

Also, I'm still very new to linux, so it might take some hand-holding... ;-)

{I'm using Mandrake 9.0, if that's of any help.}

[hilophilo]

i wanna know if linux to linux can use the full gigabit speed as well.. i have linux and windows connect through fiber and it seems speed is the same as a 100mb card. if you find any new info, i would like to know. thanks. which fiber card do you have?

[Aastrill]

This may help you somewhat...

First, ensure there are no other NIC drivers in the system (especially with NT), and that the cards are placed in the fastest possible PCI slot. i.e. the cards are capable of utilizing a 64-bit, 66Mhz PCI slot. For me, it helped to do a fresh rebuild of NT.

Then try tweaking the parameters for the NIC at the driver level, like maxing out the 'Jumbo Frames' parameter (to 16k on mine), and bumping up the Receive and Transmit Descriptors (to 256 on mine).

After all that, the maximum throughput I've gotten was about about 190Mbps between the NT machine and the Linux machine.

That's a pretty good rate for a 100MB NIC running at Full duplex, but it is only about 10% of the potential speed of a GB card.

Now I'm wondering - at what point are the disk speeds on each machine going to become the bottleneck?...

The cards are "IBM Gigabit Ethernet SX Server Adapter"s but they may have been re-branded...

[hilophilo]

yea these cards are 64bit and the pci on my mb is only 32bit. do you have any resource where i can learn how to tweak the nics at the driver level? 190mbps is still better at 100 speed. how did you check exactly the maximum throughput when data trasfereing between the two nics? i tried to use ethereal but is not giving unstable results. how fast are your HDs too? both of mine are ata133 7200rpms.

[Aastrill]

The resource I used to learn how to tweak the NIC's was just the help file included with the NT4 driver. It was fairly good, actually.

I work at IBM, and we have an in-house tool that can test maximum network throughput.

I'm actually using server-class machines with 9.1GB & 18.2GB 10k rpm Wide-Ultra SCSI drives (mirrored) on a high-speed (64-bit, 66Mhz) PCI RAID adapter.

As well, the little utility I used on the Linux machine to initiate the data copies, reports the throughput that was acheived during a copy. The highest I ever got with this tool was 9.48MB/s - a 1GB file in < 2 minutes. The utility is called 'cstream', and I found it here: http://www.cons.org/cracauer/cstream.html

Good luck! And let me know if you ever get better performance from your GB cards!

[hilophilo]

i definatey see faster speeds now. i can now transfer 700mb in 40-50 seconds. what i did is test by disabling my eth0 on my windows and my linux system. does it seem that i have some problems with my route enabling when both of the cards are enable?

but sometimes i get an error :
The request could not performed of I/O device error.

any idea?