FreeBSD and newer HDD problems ?

[Pavel Duda]

Hello,
I've recently bought new big HDD (WDC RE, 320GB) and it looks like 
FreeBSD has some troubles with it when trying to transfer files over 
network.

If I try to perform some "synthetic" test like 'dd if=/dev/zero 
of=/wdc320/testfile' then I get some decent speeds about 40MB/s. When I 
try to copy some big files from my older disk (IBM 40GB) I still have 
write about 25-27MB/s.

Problem comes when I try to copy something to disk over network (tried 
samba, ftp) disk write speed is very low - about 5-6MB/s at max.
When testing this issue I've start 'systat -vmstat 1' and noticed that 
my new disk is very busy (60-100%) and speed (MB/s) jumps up and down. 
If I write files with 'dd' or transfer them from disk 2 disk then write 
speed and disk load is almost constant (about 60%). When transfering 
files over network to old HDD then disk load is low (40-50%) and speed 
is constant (8-9MB/s).

To be sure that disk it is not some kind of disk problem I've installed 
Debian 3.1r2 with same version of samba and I get 9-11MB/s transfer 
speeds (in both directions) !!

Also it doesn't matter if I use transfer data over gigabit card or 
100mbit card. Results are similar. FreeBSD is in avarage very very slow 
(3MB) while Debian works fine (10MB). Because my server is primarily 
used for transfer files (Samba + PDC) it is crucial for me to have 
highest transfer speeds possible and I'd like to stick with FreeBSD :-/.

Does someone has any idea what could be wrong or how could I determine 
what causes this problem ?

Thanks for any advice.
     Pavel