SATA question

Alex Zbyslaw xfb52 at
Fri Feb 1 09:36:23 PST 2008

Darryl Hoar wrote:

>>maybe I spoke to soon.  While looking at dmesg in prep for doing
>>a custom kernel for my new server, I noticed an oddity.
>>ad4 - DMA limited to UDMA33, device found non-ata66 cable.
>>ad4 - <SAMSUN HE160HJ JF800-24>
>>Is this telling me the system recognized my
>>160GB 7.2K RPM Serial ATA 3Gbps 3.5-in Cabled Hard Drive as
>>a UDMA33 ?
>atapci0: <ServerWorks HT1000 SATA150 controller> port
>3,0xecb8-0xecbf,0xeca4-0xeca7,0xece0-0xecef mem 0xefdfe000-0xefdfffff irq 6
>at d
>evice 14.0 on pci3
>ata2: <ATA channel 0> on atapci0
>ata3: <ATA channel 1> on atapci0
>atapci1: <ServerWorks HT1000 UDMA100 controller> port
>177,0x376,0x8c0-0x8cf at device 2.1 on pci0
>ata0: <ATA channel 0> on atapci1
>ata1: <ATA channel 1> on atapci1
>acd0: CDRW <HL-DT-STCD-RW/DVD-ROM GCC-T10N/A102> at ata0-master UDMA33
>ad4: DMA limited to UDMA33, device found non-ATA66 cable
>ad4: 152587MB <SAMSUNG HE160HJ JF800-24> at ata2-master UDMA33
>ad6: DMA limited to UDMA33, device found non-ATA66 cable
>ad6: 152587MB <SAMSUNG HE160HJ JF800-24> at ata3-master UDMA33
>This is the copied relevant portions of demsg's output. I have only used
>pciconf to
>list devices, so am basically unfamilar with it.
>So, how do I get the system to recognize the drives as SATA ?
I think you are placing a lot of faith in an error message and that your 
drives *may* be being recognised as SATA drives with just something 
spurious (in the driver) causing this message to appear.  It looks like 
the same chipset is providing both IDE/UDMA and SATA, so maybe the 
driver is trying them as IDE first, producing the error messages, then 
finding they are SATA after all.  Just a guess

Have you tried any basic disk benchmarks?  Even a diskinfo -t should 
show you the kind of throughput your are getting, or something like

dd bs=64k if=/dev/zero of=/some/file/on/the/disk count=10000

That takes ~10 secs on my machine.  If your performance is better than 
UDMA33 then you could just ignore the message or file an informational 
PR (if there isn't one already).  Don't forget to be careful about 
bits/sec versus bytes/sec  UDMA 33 is 33MB/s which is 33*1000*1000 bytes 
but 8 times as many bits, which some applications report.

Having failed to get a definitive answer here you could also try the 
driver maintainer whom I believe to be sos at  Confirm that 
from the manpage and don't forget to mention the version of FreeBSD you 
have (6.3?)  See also this thread:



On a random SATA150 disk I get ~60017191 bytes/sec for a dd, which ~= 
60000 kbytes/sec from diskinfo and ~= 60MB/s or twice UDMA33.  I believe 
that to be about par for a modern SATA disk.

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