Termination(?) problems w/ 5.1.0pre10 (& earlier)

[Randy Gobbel]

Reccently I've started seeing unrecoverable read errors on my hard drive, a
Quantum Atlas, with a 2940UW adapter.  I'm running a 2.0.35 kernel with aic7xxx
5.1.0pre10.  A few weeks ago I started getting these medium errors frequently,
and had file corruption, after running with very few problems for almost two
years.  I thought maybe it had something to do with termination, so I switched
from auto-termination to manual.  The message I get during startup is:

aic7xxx: Cables present (Int-50 YES, Int-68 YES, Ext-68 NO)
aic7xxx: EEPROM is present.
aic7xxx: SE High byte termination Enabled

That is the correct cable configuration.

The devices I have connected are:

  Vendor: Quantum   Model: XP34300W          Rev: L915
  Type:   Direct-Access                      ANSI SCSI revision: 02
Detected scsi disk sda at scsi0, channel 0, id 0, lun 0
  Vendor: TOSHIBA   Model: CD-ROM XM-3701TA  Rev: 0236
  Type:   CD-ROM                             ANSI SCSI revision: 02
Detected scsi CD-ROM sr0 at scsi0, channel 0, id 2, lun 0
  Vendor: CONNER    Model: CTT8000-S         Rev: 1.22
  Type:   Sequential-Access                  ANSI SCSI revision: 02

Both the tape drive and CD-ROM are on the internal 50-pin cable.

I tried setting termination using the BIOS utility to HIGH on, LOW off.  This
got rid of the medium errors, but the CD-ROM and tape drive would drop offline
while the system was running.  I went back to auto-termination, and now I'm
getting these again:

scsi0: MEDIUM ERROR on channel 0, id 0, lun 0, CDB: Read (6) 17 4c 44 08 00 
Current error sd08:03: sense key Medium Error
Additional sense indicates Unrecovered read error
scsidisk I/O error: dev 08:03, sector 691474, absolute sector 1526854

The correlation between type of termination and the frequency of these errors
seems too good for this to be coincidence.

Questions:
--Is it possible that the pre11 patch addresses this problem?
--Is HIGH on, LOW off the right setup for this cable configuration, and is this
documented anywhere?
--Is there anything I should be doing to terminate these devices?  As far as I
know the last device on each cable has termination enabled, but there's not any
sort of extra widget stuck on them.  Should there be?

This is making me very nervous--this system had been running perfectly for over
a year, but the recent changes to the SCSI driver seem a bit problematic.  I
trust there's a good reason for them.

-Randy

P.S. The CPU is a PPro 200, the system was originally purchased from Vektron, a
maker of quality (NOT!) workstations. (Can you believe: no CPU fan, no thermal
grease, and a paper label left between the CPU and the heat sink?)


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