Re: Qlogic 1040B
On Tue, Feb 11, 2003 at 05:38:37AM -0600, Kelledin wrote:
>
> IIRC, the 1040B is a high-voltage differential (HVD) adapter.
> SCSI is most commonly either single-ended (SCSI-1, SCSI-2, Ultra
> SCSI) or low-voltage differential (Ultra2 or greater). HVD was
> a stop-gap standard between SE and LVD, and it's electrically
> compatible with neither one. HVD controllers only work with HVD
> drives, and vice versa. :(
>
> Just to confirm this, you can either look for a "SCSI DIFF" label
> next to the card's external SCSI port, or look for an array of
> eight yellow resistor packs--next to the external SCSI
> port--running parallel to the internal SCSI connectors. Either
> one means you've got an HVD card.
We (DEC/COMPAQ/HP) sold many QLogic 1040B-based controllers in many
different platforms over the years. Of all the ones I've seen of
those, the presence of the 1040B did not of itself indicate a
"differential" controller; I think that depends on its "deployment",
ie the surrounding circuitry.
Be that as it may, the cards I have available have neither the
"SCSI DIFF" label (at least one had "SCSI SE", others were blank),
nor the bank of resistor-packs. And these cards have always worked
fine as a single-ended controller.
So, if you *do* have the DIFF label or the resistor-packs, chances are
very good that it won't work as single-ended, ie as a replacement for
the Adaptec.
As for connecting to the external shelf, I think you need to be sure
that the "personality module" of the shelf is expecting differential
cabling, otherwise the same problem as with the internal disks will
occur.
BTW, one way that folks have gotten around the inability to boot from
the Adaptec under SRM console, is to burn a custom CD with the desired
kernel on it, but set root to an Adaptec HDD.
Good luck.
--Jay++
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Jay A Estabrook HPTC - LINUX support
Hewlett-Packard Company - MRO1-2/K15 (508) 467-2080
200 Forest Street, Marlboro MA 01752 Jay.Estabrook@hp.com
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