If I may add to this, some cards (PCI or otherwise) just absolutely INSIST
on having their own IRQ in order to work properly.  The software part of the
problem might be related to this.  Otherwise, it's purely a hardware issue,
and I concur with Russ that bus and hard drive performance is based on the
hardware.  Why your device manager does not indicate that it is a SCSI
device, however, is a question only the Window Gods can answer.

Kyle Elmblade
Distinct Computer Solutions
Sales - Upgrades - Training - Consulting
[log in to unmask]
"A closed mouth gathers no foot"

From: "Russ Poffenberger" <[log in to unmask]>
Sent: Tuesday, June 25, 2002 1:57 PM
Subject: Re: [PCBUILD] But Is it SCSI?


> Mike Whalen <[log in to unmask]> wrote:
> > Hey folks,
> >
> > I think I have a SCSI related issue, but I don't really know.
> >
> > The short question:
> > In Windows (9x or NT/XP), how does one know whether their disk drive
> > is using SCSI rather than some other interface? Is this purely
> > hardware? Or do Windows drivers play a role?
> >
> >
> > The background:
> > I work at a company that, for quite a while, used an Intel server
> > board for their products. NT4 was installed on this box solely. No 9x
> > stuff. HDD is SCSI off of a Symbios adapter.
> >
> > Well, this week I put WinME on one of these machines. I had a few
> > issues but was able to resolve them all.
> >
> > The one that took the longest to resolve, however, was the integrated
> > SCSI host adapters. WinME detected them, but could not activate them.
> > One error given was that the IRQ Holder for PCI Steering was not
> > operating properly.
> >
> > I disabled IRQ Steering. Windows them reinstalled the ACPI support
> > and .. boom .. the SCSI Host Adapters are now "working."
> >
> > (For what it's worth, I wish I understood why PCI Steering isn't
> > working. Suffice it to say that LSILogic (Symbios) says that there is
> > a known Win9x issue regarding PCI Steering and some of their "older"
> > host adapters. They give the instructions for some BIOS-area fixes,
> > but PhoenixBIOS, which is in this particular PC, is the one LSI
> > singled out as un-fixable.)
> >
> > But I kind of expected the disk drive to somehow show up as a SCSI
> > disk. It's not. So, how do I really know that I'm using the fastest
> > rate I can on the HDD? Do I need to force Windows to redetect the
> > SCSI disk now that the adapters are working? Or is it SCSI by virtue
> > of the fact that the HDD is on a SCSI chain and hardware knows what's
> > on the SCSI chain vs. the IDE chain.
>
> Mike,
>
> SCSI is a hardware standard. If the controller is a SCSI controller, you
can
> only attach SCSI disks to it.
>
> The issue with PCI steering is related to the way Windows 9x used APM for
power
> and interrupt management. This was a method where multiple PCI cards could
share
> one of the few IRQ's that are available in the PC architecture.
>
> The newer OS's (including XP and WIndows 2000) use ACPI for power and
interrupt
> management. This is a much better architecture than APM and PCI steering.
The
> only "anomaly" that people may see is that device manager may show
seemingly
> impossible IRQ's (above 15), but this is just the way ACPI creates virtual
> IRQ's. In order for ACPI to work, the BIOS must be compliant, older BIOS's
> tended to have problems. Perhaps one of the reasons why W2K and XP tend
not to
> run well on older machines.
>
> Anyway, back to SCSI, you should be able to find your answers in device
manager.
> If it shows a properly working Symbios SCSI controller device, and your
SCSI
> disks are connected to it, then everything should be fine. Also check out
the
> performance dialog, and see if all disks are running in 32bit mode.
>
>
> --
> Russ Poffenberger

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