Scsi Cabling Requirements; Setting Scsi Ids; Scsi Connector Pin-Number Assignments - IBM 866631Y - Netfinity 7100 - 8666 Hardware Maintenance Manual

channels: one external and one internal. Each channel supports up to 15 SCSI
devices. You can use the external low voltage differential (LVD) SCSI channel
connector, on the rear of the server, to connect different types of SCSI devices, such
as drives or printers. A SCSI cable connects the internal SCSI channel connector to
the hot-swap drive backplane inside the server.
Note: If you install a PCI RAID adapter to configure and manage the internal
hot-swap drives, you must move the SCSI cable from the I/O-board SCSI
connector to an internal channel connector on the RAID adapter.

SCSI cabling requirements

If you plan to attach external SCSI devices, you must order additional SCSI cables.
To select and order the correct cables for use with external devices, contact your
IBM reseller or IBM marketing representative.
For information about the maximum length of SCSI cable between the terminated
ends of the cable, refer to the ANSI SCSI standards. Adhering to these standards
will help ensure that the server operates properly.

Setting SCSI IDs

Each SCSI device connected to a SCSI controller must have a unique SCSI ID. This
ID enables the SCSI controller to identify the device and ensure that different
devices on the same SCSI channel do not attempt to transfer data simultaneously.
SCSI devices that are connected to different SCSI channels can have duplicate SCSI
IDs.
The hot-swap-drive backplane controls the SCSI IDs for the internal hot-swap
drive bays. However, when you attach SCSI devices to the external SCSI connector,
you must set a unique ID for the device. Refer to the information that is provided
with the device for instructions to set its SCSI ID.

SCSI connector pin-number assignments

The following table shows the pin-number assignments for the 68-pin SCSI
connectors.
Table 14. 68-pin SCSI connector pin-number assignments
Pin Signal
1 +Data 12
2 +Data 13
3 +Data 14
4 +Data 15
5 +Data P1
6 +Data 0
7 +Data1
8 +Data 2
9 +Data 3
10 +Data 4
34
68
Pin
35
36
37
38
39
40
41
42
43
44
1
35
Signal
-Data 12
-Data 13
-Data 14
-Data 15
-Data P1
-Data 0
-Data 1
-Data 2
-Data 3
-Data 4
Installing options
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