SCSI Tape Drive Not Recognized - "Termination" Problem?

SCSI Tape Drive Not Recognized - "Termination" Problem?

Post by Bill Polhemu » Tue, 02 Mar 2004 01:52:43



DISCLAIMER: I am a TOTAL NEWBIE when it comes to SCSI!

I bought a "vintage" HP SureStore tape autoloader to use as a backup
device for my Red Hat 9 Linux server. I also purchased an IWILL
SIDE-2936UW-E SCSI card to use with it. The card is Advansys-based.

At bootup, the Red Hat system "sees" both the card and the
drive/autoloader system just fine. However, at some point the system then
"loses" them, as I cannot access that particular SCSI bus, and a rescan of the SCSI
subssystem doesn't turn them up.

I know that the IWILL card "autoterminates," but I have no idea about the drive
itself. It has two CENTRONICS ports on it, to one of which I have
connected the card, but the other just stands empty. Could it be that I
need to get some sort of "terminator" gadget to put on that port?

Thanks in advance for any help received.

 
 
 

SCSI Tape Drive Not Recognized - "Termination" Problem?

Post by Will Dorman » Tue, 02 Mar 2004 02:05:47



> I know that the IWILL card "autoterminates," but I have no idea about the drive
> itself. It has two CENTRONICS ports on it, to one of which I have
> connected the card, but the other just stands empty. Could it be that I
> need to get some sort of "terminator" gadget to put on that port?

Yes, you need a terminator.    Unless the device itself supports
termination.   (It would likely be a jumper or dip switch if it does)

-WD

 
 
 

SCSI Tape Drive Not Recognized - "Termination" Problem?

Post by Juha Laih » Tue, 02 Mar 2004 02:37:01


(in case you're impatient: your diagnosis about improper termination
seems correct)


Quote:>DISCLAIMER: I am a TOTAL NEWBIE when it comes to SCSI!

Ok. Then the first rules. SCSI bus is a bus, and a bus needs to be
terminated at precisely the both ends (a SCSI bus also doesn't have
branches - it's a single span between the ends).

At times it also helps to remember that the SCSI host bus adapter
(card) is just one of the devices on the bus.

Quote:>I bought a "vintage" HP SureStore tape autoloader to use as a backup
>device for my Red Hat 9 Linux server. I also purchased an IWILL
>SIDE-2936UW-E SCSI card to use with it. The card is Advansys-based.

>At bootup, the Red Hat system "sees" both the card and the
>drive/autoloader system just fine. However, at some point the system then
>"loses" them, as I cannot access that particular SCSI bus, and a rescan
>of the SCSI subssystem doesn't turn them up.
>I know that the IWILL card "autoterminates," but I have no idea about
>the drive itself. It has two CENTRONICS ports on it, to one of which
>I have connected the card, but the other just stands empty. Could it
>be that I need to get some sort of "terminator" gadget to put on that
>port?

Yes -- the tape unit is designed so that it can sit in the middle of the
bus - so you could chain other devices to the other connector. But as
you don't have other devices, you'll need to terminate the bus where
it comes out of the tape unit.

You might also be able to change the SCSI cable internal to the drive
into one that has the 50-pin Cannon ("Centronics" is just the 36-pin
Cannon) connector on one end, and the suitable device connectors for the
tape drive and loader mechanism. Then set the last device in the chain
to terminate the bus (at least the tape drive should be capable of this).
But then, the external terminator should be easier to find than a cable
suitable for this. Note that with the current cable you cannot just enable
the termination for the last device, as the bus would still extend a few
centimeters past that device (to the other Cannon connector).
--
Wolf  a.k.a.  Juha Laiho     Espoo, Finland

         PS(+) PE Y+ PGP(+) t- 5 !X R !tv b+ !DI D G e+ h---- r+++ y++++
"...cancel my subscription to the resurrection!" (Jim Morrison)

 
 
 

SCSI Tape Drive Not Recognized - "Termination" Problem?

Post by Allen McInto » Tue, 02 Mar 2004 12:30:18




>DISCLAIMER: I am a TOTAL NEWBIE when it comes to SCSI!
>At bootup, the Red Hat system "sees" both the card and the
>drive/autoloader system just fine. However, at some point the system then
>"loses" them, as I cannot access that particular SCSI bus, and a rescan of the SCSI
>subssystem doesn't turn them up.

You should check /var/log/messages (and/or the output of dmesg).  The
bus shouldn't have gone away without something being printed.

Quote:>I know that the IWILL card "autoterminates," but I have no idea about the drive
>itself. It has two CENTRONICS ports on it, to one of which I have
>connected the card, but the other just stands empty. Could it be that I
>need to get some sort of "terminator" gadget to put on that port?

Cards like this usually have both an internal and an external connector.
"Autotermination" just means that you don't have to terminate the
internal or external side of the bus if you don't have anything connected
to it.  It doesn't absolve you of responsibility for termination once
you have something connected.

You ought to be able to borrow a Centronics terminator somewhere.

 
 
 

1. SCSI Tape Drive Not Recognized - "Termination" Problem?

DISCLAIMER: I am a TOTAL NEWBIE when it comes to SCSI!

I bought a "vintage" HP SureStore tape autoloader to use as a backup
device for my Red Hat 9 Linux server. I also purchased an IWILL
SIDE-2936UW-E SCSI card to use with it. The card is Advansys-based.

At bootup, the Red Hat system "sees" both the card and the
drive/autoloader system just fine. However, at some point the system then
"loses" them, as I cannot access that particular SCSI bus, and a rescan of
the SCSI subssystem doesn't turn them up.

I know that the IWILL card "autoterminates," but I have no idea about the
drive itself. It has two CENTRONICS ports on it, to one of which I have
connected the card, but the other just stands empty. Could it be that I
need to get some sort of "terminator" gadget to put on that port?

Thanks in advance for any help received.

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