ahd(4) poor performance

[Justin T. Gibbs]

--On Thursday, June 22, 2006 12:16 AM +0300 Volodymyr Kostyrko 
<arcade at synergetica.dn.ua> wrote:

> Hi all.
>
>    I have:
>
> ahd0: <Adaptec (Dell OEM) 39320 Ultra320 SCSI adapter> port
> 0xdc00-0xdcff,0xd800-0xd8ff mem 0xdfbfe000-0xdfbfffff irq 66 at device
> 7.0 on pci3
> ahd0: [GIANT-LOCKED]
> aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs
> ahd1: <Adaptec (Dell OEM) 39320 Ultra320 SCSI adapter> port
> 0xd400-0xd4ff,0xd000-0xd0ff mem 0xdfbfc000-0xdfbfdfff irq 67 at device
> 7.1 on pci3
> ahd1: [GIANT-LOCKED]
> aic7902: Ultra320 Wide Channel B, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs
>
>    Booting machine also results in:
>
> ahd0: Invalid Sequencer interrupt occurred.

This error is benign.

There have been issues reported with some recent Seagate drives and
large queue depths.  You may get better performance if you use camcontrol
to lower the queue depth to 63 or 32.  I believe that 32 is the default
used by Linux.

--
Justin