slow transfers: Samba 3.0.2a + FreeBSD 4.8 + em gigabit network card = ~125mbps

[Michael Haro]

I have a FreeBSD 4.8 server with a 3ware RAID controller in a RAID5
configuration.  The server has an Intel PRO/1000 network card in it.
I'm trying to transfer big (100MB+) files from this server to a Firewire
drive on my Windows XP workstation which also has an Intel PRO/1000 NIC.
The transfer speed of the data caps at around 120mbps.  It was lower, but
I set net.inet.tcp.sendspace to 65536 and it seemed to help.

The 3ware array says it is around 25% busy (from systat -vmstat) so I
don't think it is read performance that is the limiting factor.  The cpu
on the server is about 65% idle (from top).

The windows xp workstation is around 75% idle.  When I connect the firewire
drive directly to the server the data transfered at 160mbps.  I'd
continue doing the transfers locally except the data needs to be put on
an NTFS partition and I couldn't get FreeBSD to write to one and from the
man page it appears that write support isn't fully complete.

My question is why am I loosing ~40mbps when doing this transfer over the
network?  Both the workstation and the server are connected to Cisco
3524 switches in the copper gig port.  Both switches are connected via
the other gbic port which has a fiber gig gbic in it.  The average
utilization of these interfaces is less than 200mbit, which should leave
plenty of bandwidth for my data transfer.

Any suggestions on how to improve my performance?  Is there a better list
for me to ask this question on?

Thanks,

Michael