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Case of a 8505 exabyte drive working well under RH9 and not anymore
under Suse 9.1.

My 8505S exabyte tape drive functions (intermittently?) under a fresh
Suse 9.1 installation. Upon the fresh install, I could restore my data
files and so. But then, oh-oh, I could not read nor write after another
reboot. And then I could do it... sometimes!

As we can read at :

http://lists.suse.com/archive/suse-l...-Oct/1462.html
http://lists.suse.com/archive/suse-l...-Oct/1470.html

....people tends to think this kind of trouble is related to bad cabling
and/or terminators, which may be the culprit.

I have no terminator on my chain; the drive is the last and only device.
But I can see that such a terminator is some 70$ or so. I am not very
inclined to invest that much without being sure it would solve the trouble.

Your opinion would be valuable to me. Any ideas or recommendations?

Gaetan





PS: We have in dmesg:
gaetan@heron:~> dmesg | awk '/(sym0)|(scsi)|(EXABYTE)/'
sym0: <875> rev 0x3 at pci 0000:02:01.0 irq 10
sym0: Symbios NVRAM, ID 7, Fast-20, SE, parity checking
sym0: open drain IRQ line driver, using on-chip SRAM
sym0: using LOAD/STORE-based firmware.
sym0: SCAN AT BOOT disabled for targets 1 2 3 4 5 6 8 9 10 11 12 13 14 15.
sym0: SCSI BUS has been reset.
scsi0 : sym-2.1.18i
Vendor: EXABYTE Model: EXB-85058SQANXR0 Rev: 0781
sym0: SCSI parity error detected: SCR1=132 DBC=50000000 SBCL=0
sym0:0: ERROR (81:0) (8-0-0) (0/5/0) @ (mem dd98e028:ffffffff).
sym0: regdump: da 00 00 05 47 00 00 0e 00 08 00 00 80 00 0f 02 ff ff ff
00 02 ff ff ff.
sym0: SCSI BUS reset detected.
sym0: SCSI BUS has been reset.
Attached scsi tape st0 at scsi0, channel 0, id 0, lun 0
Attached scsi generic sg0 at scsi0, channel 0, id 0, lun 0, type 1

On Wed, 03 Nov 2004 14:30:22 -0500, Gaétan Martineau wrote:
> I have no terminator on my chain; the drive is the last and only device.
> But I can see that such a terminator is some 70$ or so. I am not very
> inclined to invest that much without being sure it would solve the trouble.

I don't know that particular drive, but I'm 99.9% certain it'll be a
narrow SCSI (i.e. 8 bit) device. If you've got that plugged into the end
of a SCSI bus segment that's got wide SCSI (16 bit) devices on it then
you'll need a wide SCSI terminator on the end of the bus (and to disable
the termination on the tape drive as otherwise you'd end up with the
lower 8 bits of the bus dual-terminated at that end)

Do check that your tape drive is jumpered to supply parity information
(assuming the controller card's set to detect it - but it looks like it
is) as that would screw things up too.

Try local computer surplus stores, universities etc. to see if they have a
terminator. They're extremely expensive new as you've already found out
(same with SCSI cabling)

cheers

Jules

On 2004-11-03, Gaétan Martineau <gmarti@pasdespammediom.qc.ca> wrote:

> Case of a 8505 exabyte drive working well under RH9 and not anymore
> under Suse 9.1.

Did you change any cabling? Add or remove devices from the chain? Change
SCSI-IDs?

> My 8505S exabyte tape drive functions (intermittently?) under a fresh
> Suse 9.1 installation. Upon the fresh install, I could restore my data
> files and so. But then, oh-oh, I could not read nor write after another
> reboot. And then I could do it... sometimes!
>
> As we can read at :
>
> http://lists.suse.com/archive/suse-l...-Oct/1462.html
> http://lists.suse.com/archive/suse-l...-Oct/1470.html
>
> ...people tends to think this kind of trouble is related to bad cabling
> and/or terminators, which may be the culprit.
>
> I have no terminator on my chain; the drive is the last and only device.
> But I can see that such a terminator is some 70$ or so. I am not very
> inclined to invest that much without being sure it would solve the trouble.

$70 for a terminator? The EXB-8505 is just a regular 50-pin device, and
looking at the product manual
(http://www.mwtss.com/Reference%20Lib...yte%208505.pdf)
appears to use resistor packs for termination. Check that these are
in place, and if you have any other devices on the same cable, make sure
they come before the tape drive and are not themselves terminated.

If the tape drive doesn't have the terminators, put another deive after it
on the cable and ternminate that device. Or add a simple passive
terminator to the cable.

--

-John (john@os2.dhs.org)

John Thompson wrote:
> On 2004-11-03, Gaétan Martineau <gmarti@pasdespammediom.qc.ca> wrote:
> $70 for a terminator? The EXB-8505 is just a regular 50-pin device, and
> looking at the product manual
> (http://www.mwtss.com/Reference%20Lib...yte%208505.pdf)
> appears to use resistor packs for termination. Check that these are
> in place, and if you have any other devices on the same cable, make sure
> they come before the tape drive and are not themselves terminated.
>
> If the tape drive doesn't have the terminators, put another deive after it
> on the cable and ternminate that device. Or add a simple passive
> terminator to the cable.

I think you are right. Searching the net, I could get a 50 pins
terminator that (hopefully) will suit me. But I am pretty sure this is
the reason...

I will then plug and test, then be back here to inform about the results.

Thanks to all

Gaetan