SUMMARY Request Consult on a 4/630 which Hangs and Needs Power Cycle

Date: Wed Dec 23 1992 - 18:44:56 CST

Seasons Greetings.

We found several things which needed attention on our 4/630. We have
been operating for one week now without problems. Here is a brief

(1) Doubly Terminated SCSI Bus: This 630 has two SCSI busses. Atop the
630 near a SCSI connector which is at the rear of the machine, there is
a small access panel held in place by two screws. Beneath that panel was
a group of three terminators. As our staff had been unaware of the
presence of these terminators, we had terminated the same bus at an
8mm tape drive. Double termination.

(2) Bent pin in SCSI cable, Same Bus: We detected a bent pin in a SCSI
connector on the same bus. This may have caused an intermittency. We
replaced the cable.

(3) Bad SCSI Disk Drive: After these items were corrected, a disk on the
same bus started logging lots of errors. We replaced it.

(4) Ferrite Wraps on SCSI Cables: Sun provided some SCSI cables with
ferrite wraps at the ends. I guess they suspected some EM interference.

(5) Seating of SCSI Connectors: We noted that the other SCSI bus
connects to the 4/630 using a miniconnector atop the machine. This
connection was easily wiggled and may have been intermittent. We
carefully seated the connection and plan to provide strain relief.

(6) Software Patches: We also installed several patches recommended by
Sun for SunOS 4.1.3, sun4m.

So far, so good. This hanging was quite frustrating because nothing
was ever logged, and it took a power cycle to recover the machine.
No dump was possible. Thanks for your letters.

Bill Shorter

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