Re: Mixing SCSI II and SCSI II Fast on a UDB...

[Ryan Kirkpatrick <rkirkpat nag cs colorado edu>]

On 30 Jul 1998, Eric Smith wrote:

> Ryan Kirkpatrick <rkirkpat@nag.cs.colorado.edu> wrote:
> > 	With the FAST SCSI / Sync SCSI enabled for the NCR card in the
> > UDB, I just got hard lockups, or screens and screens of memory failures
> 
> The SCSI bus in the UDB is not properly designed.  If you don't use 
> external devices, the bus is only singly terminated.  If you do use external
> devices (and an external terminator), the bus will be doubly terminated, but
> there will be a stub from the riser to the internal disk.  Make sure that
> your external bus terminator is an *active* terminator, not passive.

	Hmm... That would probably explain the strange behavior I get from
the scsi bus sometimes. What happens if I have only external devices and
no internal devices?

> If you want both reliability *and* high performance on your SCSI bus, I'd
> suggest using a PCI SCSI card.  I've had good results with inexpensive
> 53C8xx cards.  The issue isn't the chip, it's the termination.

	Are there any brands you can suggest? Should anything with the
53C8xx chip work with Linux/Alpha and be bootable from? Also, most modern
PCI SCSI cards have thier own BIOS/setup program (i.e. A message during
boot about pressing x keys to enter setup). How is this accessed
from an Alpha, or is it even possible? Lastly, is Symbios a good brand
name, such as thier NCR 53C810 PCI SCSI card?
	Sorry about all of the questions, but SCSI cards and Alphas I
understand independently, and when the former is integrated into the
latter, but when add the former to the latter in the form of a PCI card I
am a little lost. Thanks!

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|  Ryan Kirkpatrick  |  Boulder, Colorado  | rkirkpat@nag.cs.colorado.edu  |
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