[lug] AHA3940UW RH & tape drive

Installer jkarns at csd.net
Thu Feb 22 09:06:15 MST 2001

It sounds to me like the problem is most likely a kernel config
issue.  But here's some general information for dealing with SCSI...

Length of the SCSI cable is important.  For a 50-pin cable, I believe the
max length is something like 6 feet.  For 68 pin, I believe it's less.  
The rule of thumb is the shorter (and thicker) the better.  Another
important issue is the use of a terminator.  SCSI specs call for
termination at both ends of the bus.  Most modern controllers implement
auto termination on the card, which means that it will take of the issue
on the card end of the bus.  OTOH, if you should happen to connect both
internal and external devices (thus placing the card in the middle of the
bus), you would need a terminator on the ends of each cable, and the card
would remain unterminated.  All that said, in many instances you can get
away without a terminator, especially when you have only a single device
connected with a short cable.

Try viewing the device info from the cards BIOS routines.  This should be
accessible during system boot, when the Adaptec card BIOS banner is
pisplayed, accompanied by a msg similar to "Ctrl-A for Menu".  This should
bring up a menu with various options, one of which should be similar to
"Display device information".  If you don't see the tape drive somewhere
in the device list, then it's most likely a cable issue or the tape drive
is not talking to the SCSI bus.  Also check the SCSI device id of the tape
drive, which is usually set via jumpers.  Each device on the bus must have
a unique id.  Device # 7 is usually reserved for the card.  Selecting
device 0 or 1 for the tape drive should be a safe bet.

On Wed, 21 Feb 2001, David A Merritt said:

>Sorry if this has already been mentioned, but for Adaptec SCSI
>controllers, the bios is not loaded unless there is a bootable
>device on the chain, but it (the bios code) isn't needed in order to
>use tape drives on the chain, so that isn't the problem here.
>Sorry I can't speculate what the problem is, but I have a similar
>setup (with 2940) and a DAT but no bootable devices (thus bios code
>not loaded) and it works fine.  Didn't do anything special either.
>On Fri, 16 Feb 2001, D. Stimits wrote:
>> Anders Knudsen wrote:
>> >
>> > Having trouble with RH7 seeing this tape drive.
>> > I installed an adaptec 3940 controller (it was lying around) and attached an
>> > exabyte scsi 8mm tape drive to it. Want to use this for back up. This is the
>> > only thing connected to the adapter card. When I boot, the adapter says that
>> > the tape drive is on channel B at scsi id 0. Then it says scsi bios not loaded.
>> > When the RH7 kernel boots, it says scsi: 0 devices found.
>> > I cannot access /dev/st0.
>> > Am I missing something?
>> > I checked the various HowTos, nothing helped. I even restarted with a tape in
>> > the drive. Still nothing.
>> > BTW, this drive works fine with Windoze.
>> > TIA for any info...
>> > -Anders.

John Karns                                              jkarns at csd.net

"Those who cast the vote decide nothing; Those who count the vote decide
everything." - Joseph Stalin 

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