Ref: 11640069
Title: Problem with Tandberg Drives Backing Up Large Amounts of Data
Date: 4/9/90

Copyright 3Com Corporation, 1991.  All rights reserved.

As of August 1989, problems have been seen with Tandberg tape drives
backing up amounts of data larger than the tape's capacity, requiring
a tape change, or backing up expansion units.  (This is not specifically
an expansion unit problem, but it occurs most frequently because having
an expansion unit gives you more than 150 MB of data.)  The problems
occur on the Tandberg's SCSI interface.

When changing the tape to begin backup on an expansion unit, the
backup may fail at the start, with one or all of the following
error messages:

    Internal error 9. rx=16
    Tape drive error; miscellaneous
    Unrecoverable error; operation halted

Also, when backing up an expansion unit, the following errors may
appear in the BACK_LOG file:

    Backup completed unsuccessfully
    (x) MB written to tape
    Unrecoverable error; operation halted

To correct the problems, replace the SCSI terminator in the disk
expansion box with a new-style external AMP SCSI Termination
Connector (P/N 6583-00):

1.  Power off the server and expansion box.  Remove the cover of
the expansion box.

2.  On each Adaptec 4525 controller, there are two dual in-line
sockets immediately behind the connector for the SCSI cable.
One of the controllers will have terminators installed in both
sockets.  Remove both terminators and set aside.

3.  Replace the cover of the expansion box.

4.  On the back of the expansion box, there are two Centronix D-
style connectors, one of which has an external SCSI cable
attached to it.  Put the termination connector on the other
(unused) D-style connector, nesting it and clamping the wire
clips on it.  If the fit is tight, work it on carefully.

Or, if you have already checked that the Tandberg tape unit has
the correct hardware and PROM revision level and made sure you
are using the latest TAPE.SYS file, you may choose to replace the
Tandberg tape drive with an Archive tape drive.  You will need a
new style SCSI cable (3612-01) and a new TAPE.SYS file dated
9/30/88 or later.  Refer to existing installation documentation
for changing the tape drive.

