problem with adaptec 3940 not finding drives

[Chris Evans]

I am newish to linux and pretty ignorant of scsi things though 
they've always worked for me under windoze and windoze NT 
before but I'm sick of M$ and trying to shift as much as I can to 
linux (no offence to BSD: it's just that some stats. s'ware I want 
comes prepackaged for Debian which cuts out some of the 
mistakes I can make!)

I had created a Debian (Hamm) system on a machine that had 
previously run NT.  Controller is an adaptec 3940.  I changed the 
motherboard from a 90MHz one to a 300MHz K6 board.  Now I find 
the system only recognises two of the four hard drives that are 
there.  I decided to clean everything up and rebuild from scratch.  
Now I get the following on booting system with clean resc1440.bin 
floppy:

<4> Detected scsi CD-ROM sr1 at scsi0, channel 0, id 3, lun 0
<6> (scsi1:0:-1:-1) Scanning channel for devices
<4> (scsi0:-1:-1:-1) Bad scbptr 255 during SELTO.
<4> (scsi0:-1:-1:-1) Referenced SCB 255 not valid druing SELTO
<4>          SCSISEQ = 0x12 SEQADDR = 0xa SSTAT0 = 0x15 
SSTAT1 = 0x8a
<4> scsi    :   detected 2 SCSI cdroms 2 SCSI disks total.

The three error lines are then repeated but with SSTAT1 = 0x88 
later.  dmesg shows a time out, I'm not sure if that comes up every 
time or not.

I get the same message whether I plug the drive chain to channel A 
or B on the controller and both have the lines starting (scsi0:-1:-1:-
1) which suggests to me this is something to do with that channel 
on the controller, as handled by linux, not something to do with the 
drives. 

The controller says all the drives (four hard discs, two CDROMs) 
are there whichever channel I plug the cable to.  It also says that 
the discs verify fine.  Only the one drive is terminated, the IBM at 
the end of the chain which is one of the drives that is reliably found. 
 Things seem to go wrong in about the same way regardless of 
which drives (except the IBM obviously!) I plug into the cable or 
leave out.  All plugs on the cable seem to seat well on the drives 
and the controller.  The setup worked fine with the 90MHz P5
motherboard before with Award BIOS, the new board has a later 
Award BIOS.  Linux initialisation of the two SCSI channels appears 
to go fine, problem appears to be at the next stage.  

What are SCBS?!!  What is a SELTO?  What are those hex 
values?  More to the point, what should I do next?  Sorry if this is
rather dumb for this list but debian-user couldn't help but pointed me
to linux-scsi where I've asked this twice.  I'm happy to provide any 
more information and try just about anything to get this right! 

TIA,


Chris
Chris Evans, R&D Consultant,
Tavistock & Portman NHS Trust

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