Test 7 - Scsi-A Bus (Models 30 And 40); Test 6 - Scsi-A And Scsi-B Bus (Model 30) - Digital Equipment VAXstation 3100 Maintenance Manual

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Troubleshooting 35
2.12 TEST 7 - SCSI-A Bus (Models 30 and 40)
The SCSI-A bus on model 30 or model 40 is an internal device bus. It only
contains two possible devices: the TZ30 tape drive and the system disk (RZ22
or RZ23). The TZ30 tape drive holds small computer system interface (SCSI)
address ID 5 and the system disk holds SCSI address ID 3. Other devices
may be connected to this bus but the performance of the operating system will
be degraded severely. If there are other devices on the SCSI-A bus, be sure
to note their SCSI address ID and type of device since they may be the cause
of a problem on the bus.
The procedures for troubleshooting devices on any SCSI bus are similar.
You must determine what drives are installed on the SCSI bus you are
troubleshooting by physically looking at the drives and their cables and by
entering SHOW DEVICE. SHOW DEVICE is a command which lists all
drives and devices operating in the system and lists which drive is on which
SCSI bus. You must also know the different codes for each of these drives so
you can identify a faulty drive just by looking at its code in the configuration
table and when running the system exerciser. Two items to remember when
troubleshooting the SCSI-A bus in either the model 30 or model 40 systems
are: TEST 7 starts the diagnostics and the SCSI-A bus is an internal only bus,
which means that no external expansion boxes can be connected to this bus
(the SCSI-B bus is an internal and external SCSI bus). Refer to Section 2.15
to troubleshoot any SCSI bus (SCSI-A or SCSI-B).
2.13 TEST 6 - SCSI-A and SCSl-B Bus (Model 30)
Two MSC modules are available for the model 30 system. The SCSI/SCSI
MSC module contains two SCSI buses (SCSI-A and SCSI-B) and the
ST506/SCSI MSC module contains one SCSI bus (SCSI-A) and one bus for
the RX23 diskette drive (STRG-1). TEST 6 runs diagnostics on the SCSI-A
bus when the ST506/SCSI MSC module is installed and on the SCSI-B bus
when the SCSI/SCSI MSC module is installed. The ST506/SCSI MSC module
is replaced by the SCSI/SCSI MSC module once an additional adapter module
is available for the RX23 diskette drive. This adapter module interfaces the
RX23 onto one of the SCSI buses on the SCSI/SCSI MSC module. To
determine which MSC module is installed, display the configuration table
(T 50) and look for STRG-1, SCSI-A, and SCSI-B. If STRG-1 is listed, the
ST506/SCSI MSC module is installed. If SCSI-A and SCSI-B are listed, the
SCSI/SCSI MSC module is installed.
The SCSI bus for the TEST 6 diagnostics is an internal and external bus. It can
contain three internal devices: the internal TZ30 tape drive, the system disk
(RZ22 or RZ23 ), and a user disk, and up to three external devices: the TKSOZ
expansion box, the RZ55 disk expansion box, and the RRD40 expansion box.
If there are any other devices on the SCSI bus, be sure to note their SCSI