SUMMARY: Resetting SCSI for "locked" Exabyte

From: Tim Gibbs (Tim.Gibbs@src.bae.co.uk)
Date: Wed May 12 1993 - 03:42:12 CDT


A *long* time ago I posted to this group for suggestions on
how I could stop my exabyte tape drive from "locking up" and
becoming inaccessible.
The problem is this :-

Sparcserver 4/490 running 4.1.3, internal exabyte 8500, QIC150 1/4inch
tape drive (all SUN supplied)
The exabyte occassionaly locks up, if there is a
process trying to access the tape then it is stuck in a 'D' state according
to ps, this process cannot be killed or interrupted. Pressing the unload
tape on the front of the tape drive also has no effect.
Previously my only recourse has been to reboot the machine, which 'cures'
the problem. This problem has existed for me since 4.1.1 and also when
the drive was an exabyte 8200.
 No patch supplied to me by SUN has fixed the problem.
Since several other people have also complained of the same type of
problem, I'm posting the best method I know of unlocking the drive

There is a SUN patch 100519-01 which will reset the SCSI bus
When the tape drive "locks up" I run this program which resets
the SCSI bus, and the tape drives become useable again, without the
pain of a reboot, I have run this many times with no apparent problems.

Here's the patch README, although it specifically mentions CDROM,
it works on tapes too !

##################################################################

Patch-ID# 100519-01
Keywords: CD, CDRROM, SCSI, bus, reset, address, busy, device
Synopsis: SunOS 4.1.1: cdrom becomes inaccessible after normal use
Date: 6/Apr/92
 
SunOS release: 4.1.1
 
Topic: Need method to reset SCSI bus.
 
BugId's fixed with this patch: 1072950, 1052372

Architectures for which this patch is available: All

Patches which may conflict with this patch:

Note: Using this patch will terminate any active tape or cdrom I/O
      on the scsi bus. Other SCSI I/O (disk, etc.) should recover
      correctly from the reset.

Obsoleted by:

Problem Description:
   After using the CDROM for a while, doing multiple mounts, umounts,
   and ejects, operations begin to fail with the message "device busy"
   or "no such device or address".

   This patch is a script that creates a Makefile and a C source file.
   It then uses make to build a loadable device driver module from
   the source file, modload's the driver which does a scsi reset,
   then modunload's the driver.

INSTALL:

1) Login as root.

2) Determine SCSI controller type (ctrlr_type) esp, sc, se, si, or sm.

3) Determine SCSI controller number (ctrlr_num).

4) enter: sh ./SCSI_Reset <ctrlr_type> <ctrlr_num>
   
   The default ctrlr_type is 'esp' and ctrlr_num is '0'.

   WARNING: failure to specify the correct ctrlr_type or ctrlr_num
            _will_ result in a system panic.

Note: Using this patch will terminate any active tape or cdrom I/O
      on the scsi bus. Other scsi I/O (disk, etc.) should recover
      correctly from the reset.
##################################################################

--
Tim Gibbs                                  Email: gibbs@src.bae.co.uk
FPC 267, British Aerospace PLC,            Tel:   +44-272-363533
P.O. Box 5, Filton,                        Fax:   +44-272-363733
Bristol. BS12 7QW      



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