sata slave on intel ICH7

[Dane Miller]

Hi,

FreeBSD 6.3-RELEASE detects one of my three SATA disks as "ata2-slave".
I thought SATA did away with the master/slave ugliness of PATA. 

Thinking maybe this was misleading output from FreeBSD, I did some
concurrent writes using dd.  Sure enough, I see poor performance on
concurrent writes to ad4 and ad5 (ata2-master and ata2-slave), while I
see good performance on concurrent writes to ad4 and ad6 (ata2-master,
ata3-master).  I can provide more details on the write tests I
performed, but I'm more interested in *why* FreeBSD detects one of my
SATA disks as a slave...

Here are some details:

6.3-RELEASE FreeBSD 6.3-RELEASE #0 i386
Motherboard: Intel S3000AH
BIOS: SATA Mode is set to "Enhanced" (as opposed to "Legacy")

# atacontrol list
ATA channel 0:
    Master:      no device present
    Slave:       no device present
ATA channel 1:
    Master:      no device present
    Slave:       no device present
ATA channel 2:
    Master:  ad4 <WDC WD2500KS-00MJB0/02.01C03> Serial ATA II
    Slave:   ad5 <WDC WD2500KS-00MJB0/02.01C03> Serial ATA II
ATA channel 3:
    Master:  ad6 <WDC WD2500KS-00MJB0/02.01C03> Serial ATA II
    Slave:       no device present

# grep -i ata /var/run/dmesg.boot 
atapci0: <Intel ICH7 UDMA100 controller> port
0x1f0-0x1f7,0x3f6,0x170-0x177,0x376,0x30b0-0x30bf irq 18 at device 31.1
on pci0
ata0: <ATA channel 0> on atapci0
ata1: <ATA channel 1> on atapci0
atapci1: <Intel ICH7 SATA300 controller> port
0x30c8-0x30cf,0x30e4-0x30e7,0x30c0-0x30c7,0x30e0-0x30e3,0x30a0-0x30af
mem 0x88200000-0x882003ff irq 19 at device 31.2 on pci0
ata2: <ATA channel 0> on atapci1
ata3: <ATA channel 1> on atapci1
ad4: 238475MB <WDC WD2500KS-00MJB0 02.01C03> at ata2-master SATA150
ad5: 238475MB <WDC WD2500KS-00MJB0 02.01C03> at ata2-slave SATA150
ad6: 238475MB <WDC WD2500KS-00MJB0 02.01C03> at ata3-master SATA150

Any guidance on this would be greatly appreciated.  Thanks,
Dane

-- 
Dane Miller
Systems Administrator
Greatschools, Inc
http://www.greatschools.net