[nSLUG] SCSI novice, hardware qry

gnwiii at gmail.com gnwiii at gmail.com
Wed Mar 8 08:13:29 AST 2006

On 3/8/06, Mike Spencer <mspencer at tallships.ca> wrote:
> Sliding wayy down the scale from the ongoing discussion of good
> commercial server strategy...
> I'm having trouble getting a SCSI scanner to work: I can't seem to
> talk to the SCSI card(s).
> Are there any well known, possibly non-obvious gotchas that I might be
> missing?  Details follow if you're kind enough to read on.
>    Linux 2.4.29 kernel
>    AHA 1520A and AHA 1540B/42B SCSI cards (not installed simultaneously)
>    Have corresponding drivers (aha152x.o and aha1542.o)
>    PII and P133 CPUs -- same vintage more or less as the SCSI cards.
>    Microtek ScanMaker II-XE and (ca. 24") SCSI cable, attached and
>    turned on at boot, scanner channel selector set.

How is the SCSI bus terminated?  Some devices have built-in
termination that is switch selectable.  Normally you terminate the
last device on the chain.  You can get external terminators that go
between the cable and the device.  If you have to purchase one, get an
"active" terminator.

Try a different cable.  Cables are responsible for 70% of SCSI
problems, the other 30% are due to incorrect cabling/termination.

>    Have the PDF manuals for the cards, have the jumpers set to specs
>    (insofar as I understand them).
>    Have tried both cards in various slots of one machine (PII) and one
>    card in the only usable slot of another (P133).  Results vary:
>    Driver module won't load, module loads but can't find a channel to
>    talk to the card etc.  At boot, the BIOS reports trying to contact
>    the SCSI card and failing.  Both machines work fine otherwise.

Maybe an interrupt conflict.  I think those are IDE cards.  You may
have to set interrupts (via jumpers) and I/O ports and you probably
need to give some settings to the drivers, although many will use the
factory default settings for the card.

You can map out what interrupts are used for what, on a 2.6 kernel it is
"ls -R /proc/irq"

There is a myth that you have to use an older kernel with old hardware.
Not true, although a) you may have to hunt to find a kernel compiled
for an older CPU, and b) there are some (usually expensive) devices
where the vendor has gone out of business and the only drivers are in
binary form.

> Should I just give up on these old cards and get a new one?  Or is a
> SCSI scanner, SANE support notwithstanding, a bad deal?  Clever
> hardware check or hack I never heard of?

How much is your time worth?    It is good that you have 2 cards, but
you also need spares of the cable, terminator, and a 2nd SCSI device
for testing (I use an old SCSI CD drive).

> I've had such good luck hitherto with old hardware that I just can't
> believe that I can't make this work.  :-)
> I don't have detailed error messages logged but could get them.

I think I've seen more of those than I ever wanted.

George N. White III <aa056 at chebucto.ns.ca>
Head of St. Margarets Bay, Nova Scotia


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