fasttrack 100 and low write speed

[Putinas]

Hi all,

I have in my 4-STABLE system 2 drives in RAID 0 configuration:
ATA channel 2:
    Master:  ad4 <WDC WD600AB-22CBA1/04.07B04> ATA/ATAPI rev 5
    Slave:       no device present
ATA channel 3:
    Master:  ad6 <WDC WD600AB-22CBA1/04.07B04> ATA/ATAPI rev 5
    Slave:       no device present
and following controller
atapci0: <Promise ATA100 controller> port 0x9800-0x983f,0xa000-0xa003,0xa400-0xa407,0xa800-0xa803,0xb000-0xb007 mem 0xf0800000-0xf081ffff irq 9 at device 11.0 on pci2
( only this controller is sitting on irq 9 )
and I have noticed very low write speed with samba , transfer speeds are lower then 1 mb/s, here is output from iostat
      tty             ad2              ad4              ad6             cpu
 tin tout  KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s  us ni sy in id
   0 9813  0.00   0  0.00   0.00   0  0.00   0.00   0  0.00  16  0  5  3 76
   0   77  0.00   0  0.00  128.00   7  0.87  128.00   7  0.87   0  0  2  9 88
   0   78 128.00   1  0.12  128.00   7  0.87  128.00   7  0.87   1  0  4  9 87
   0   80  0.00   0  0.00  128.00   7  0.87  128.00   8  1.00   0  0  5 14 81
   0   79  0.00   0  0.00  128.00   6  0.75  128.00   6  0.75   0  0  2  3 95
   0   78  0.00   0  0.00  87.00  27  2.29  75.69  26  1.92   2  0  8 22 68

when read speed goes more then 8mb/s transfer via wire already, after playing with samba settings I found out what writing to ad2 drive which is not RAID0 part goes up to 7-8Mb/s without problem. So all my guessing about wrong samba or network tuning was wrong and I come to the point:
why writes to array are so slow ? Is it "normal" or there is a way to fix this somehow ?

Please reply me directly to e-mail ( if there will be any ;-)

Thank you,
Putinas