Ref: 11640064
Title: Terminating the Server's SCSI Bus
Date: 4/9/90

Copyright 3Com Corporation, 1991.  All rights reserved.

Your server's hard disk drive, tape drive, and expansion units
are serially connected to the server by a bus conforming to Small
Computer Systems Interface (SCSI) standards.

For devices on the SCSI bus to work properly, the first and last
devices on the SCSI bus must have SCSI terminators installed, and
all devices in between must be free of SCSI terminators.

To run 3+Backup successfully, you must properly set up your SCSI
devices to either terminate or not terminate the SCSI bus for
your server.

Tape drives on the 3Server3 server require SCSI bus terminating
resistors to terminate one of the two SCSI buses on these
servers.  See "The 3Server3" in the 3Server Drive Options Guide
for details.

Tape drives on the 3Server386 and 3Server/500 servers should not
have terminating resistors because they are in the middle, not at
the end, of the SCSI bus.

Exabyte 2.3 GB tape drives installed on a 3Server386 require an
external SCSI terminator (supplied with the 2.3 GB tape drive
option) placed on the 3Server386 external SCSI port.

The SCSI board in the 3Server/500 server is shipped with
terminating resistors installed.  If you add an expansion unit to
this server, you must remove the terminating resistors from
locations RP1, RP2, and RP3 and place a SCSI terminator on the
expansion unit.  See "SCSI Termination" in the 3Server Drive
Options Guide for details.

As a rule, 3Com servers are shipped with their SCSI devices
properly configured for their particular SCSI bus.  However, if
your server's tape drive was recently installed or changed, it
may require SCSI terminating resistors to be installed or
removed.  See the 3Server Drive Options Guide for details on
finding, inserting, or removing these resistors.
