SATA HDD seen at UDMA33

[Erik Trulsson]

On Fri, Jun 29, 2007 at 05:10:27PM +0000, Alin Tuhut wrote:
> Update
> OS is a 6.2-RELEASE on AMD64.
> Here is the output of the "diskinfo -t ad4" command.
> 
> ad4
>         512             # sectorsize
>         250059350016    # mediasize in bytes (233G)
>         488397168       # mediasize in sectors
>         484521          # Cylinders according to firmware.
>         16              # Heads according to firmware.
>         63              # Sectors according to firmware.
> 
> Seek times:
>         Full stroke:      250 iter in   5.432801 sec =   21.731 msec
>         Half stroke:      250 iter in   3.877507 sec =   15.510 msec
>         Quarter stroke:   500 iter in   5.912781 sec =   11.826 msec
>         Short forward:    400 iter in   3.795284 sec =    9.488 msec
>         Short backward:   400 iter in   2.920622 sec =    7.302 msec
>         Seq outer:       2048 iter in   0.285495 sec =    0.139 msec
>         Seq inner:       2048 iter in   0.333242 sec =    0.163 msec
> Transfer rates:
>         outside:       102400 kbytes in   1.454757 sec =    70390 kbytes/sec
>         middle:        102400 kbytes in   1.708399 sec =    59939 kbytes/sec
>         inside:        102400 kbytes in   2.725383 sec =    37573 kbytes/sec
> 
> ----- Original Message ----
> From: Alin Tuhut <alint7 at yahoo.co.uk>
> To: freebsd-questions at freebsd.org
> Sent: Friday, 29 June, 2007 7:36:40 PM
> Subject: SATA HDD seen at UDMA33
> 
> Hello,
> 
> I have a SATA HDD (http://www.samsung.com/Products/HardDiskDrive/SpinpointPSeries/HardDiskDrive_SpinpointPSeries_SP2504C.asp) in my server but it shows:
> 
> ad4: 238475MB <SAMSUNG SP2504C VT100-50> at ata2-master UDMA33
> 
> I've seen here http://monkey.org/freebsd/archive/freebsd-stable/200705/msg00393.html that it's detected at ata2-master SATA150 
> 
> Can anyone please tell me why it's seen at UDMA33 and how can I fix this so it's detected correctly? I'm running FreeBSD 6.2.
> 

Short answer:

  Don't worry that it says 'UDMA33' - your disk runs at full speed anyway.


Longer answer:

  This looks like a problem with the disk controller rather than with the disk
  itself - it would not matter if you changed the HDD to a different model.

  FreeBSD does apparently not fully support your disk controller and therefore
  treats it as a 'generic' ATA controller - which limits the detected speed to
  UDMA33.  If it had been a PATA controller it would indeed also have run at
  a max treansfer speed of 33 MB/s.  A SATA controller however will run at 150
  (or 300 for newer disks/controllers) MB/s regardless of what FreeBSD shows.

  The transfer rates that diskinfo reports that you quote above shows that the
  disk does indeed run at faster than UDMA33 speed.  The numbers quoted are
  indeed almost exactly what I would expect from that particular HDD running
  at full speed.

  To fix this so that FreeBSD detects your controller correctly you would
  need to update the ata(4) driver so that it gets support for your
  controller.  This support might already exist in some newer version of
  FreeBSD, or it might not - you haven't said what controller you are using
  so I have no way of knowing the status of its support in FreeBSD.



-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at student.uu.se