Very Computer

The system is running FreeBSD 3.2-RELEASE, and my intent is to use it
as a Samba server for a Win95 client system used by our children.  High
throughput is =not= required, so I believe the 486 (which I happened to
have lying around) should be good enough.

The drive works flawlessly on a 233-MHz Pentium with on-board IDE, but
on the 486 it is unreliable; sometimes I get interrupt timeouts or other
errors, and sometimes the data read from the drive is simply wrong even
though no explicit error message was generated.

Note that FreeBSD 3.2 is perfectly capable of using a hard drive of this
size (I do =not= need special software to break the 8.4GB barrier).  The
drive's full size =is= detected and reported at boot time.

I want to fix the problem as inexpensively as I can -- by changing some
driver setting in the FreeBSD kernel if possible, or else by using a
different ISA interface card (note that this 486 motherboard does not
have any PCI slots or onboard IDE).  I assume upgrading to a Pentium
board will make the problem go away, but I would consider this a last
resort.

Any suggestions?

I suspect the signal timing of old ISA IDE controller was very sloppy by
ATA-2 standards (they were ATA-1), and won't work with ATA-3 drives. Maybe
your BIOS has ISA timing settings.

You can still buy these cards, maybe new ones are better.

Quote:

> The drive works flawlessly on a 233-MHz Pentium with on-board IDE, but
> on the 486 it is unreliable; sometimes I get interrupt timeouts or other
> errors, and sometimes the data read from the drive is simply wrong even
> though no explicit error message was generated.

        > Check that there are no IRQ, DMA I/O conflicts Especially
        > with your network card.  I use and recommend the DOS version
        > of Dr Hardware http://www.online.de/home/gebhard/

Thanks.  I did this, and found no conflicts.  I also checked all IRQ,
DRQ, and I/O port assignments carefully when I assembled the system.
Further, an older drive (212MB Western Digital Piranha 4200) works
perfectly on the same IDE controller, in the same slot, with the same
cable.

        > Check for a loose cable connection.  Replace the cable with
        > a known good cable.

I did this too.  The cable is good and is connected properly, and I
also tried another cable (with no difference in disk misbehavior).

        > Is the I/O card in a 16-bit slot?

Yes.  All the slots are 16-bit.  Further, as I said, another (older)
drive works perfectly off the same IDE controller in the same slot.

        > If your video card is working correctly, swap slots with it.

That test wouldn't help in this case, because I'm using an old 8-bit
video card with a monochrome monitor on this system.  But, as I said,
all the slots on this motherboard really are 16-bit slots; the docu-
mentation for the board says so, and I've routinely used 16-bit cards
in all the slots (at one time or another) without ever having problems.

        > If it still doesn't work you might want to consider buying
        > a new I/O controller card.  *But* you might find, that for
        > a few dollars more, you can buy a used pentium motherboard
        > with CPU at www.ebay.com

Good point.  I'll keep that possibility in mind.

After taking the system apart, rechecking IRQ/DRQ and other settings,
and putting it back together in a slightly different way, I managed to
fix the problem.  The big drive works just fine now.

I had been using two IDE interfaces (one for each drive), in an effort
to optimize performance.  I thought I had set up the two cards so they
wouldn't clash, but I may have been mistaken.  I reconfigured the system
(for the time being) to run both drives off a single IDE interface.

I then stress-tested it by NFS-mounting the large drive, reading large
amounts of data from it on another computer in our home, and comparing
the data with an original copy on a CD-ROM.  (It did OK.)

I'll probably still try upgrading this box to a Pentium eventually --
or at least try again to set it up so each drive is on its own IDE card
-- but for the time being it seems to be working OK for what I need it
to do.