IBM Netfinity 4500R, Hardware Maintenance Manual

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Installing options
65
Ultra3 SCSI ports
Your server has an integrated dual-channel Ultra3 small computer system interface
(SCSI) controller. This controller supports two independent Ultra 160/m SCSI
channels: one internal and one external. Each of these channels supports up to 15 SCSI
devices. In addition, this controller uses:
• Double-transition clocking to achieve high transfer rates
• Domain name validation to negotiate compatible data transfer speeds with each
device
• Cyclic-redundancy checking (CRC), instead of the usual parity checking, to
significantly improve data reliability
• An active terminator on the system board for SCSI bus termination
You can use the external LVD SCSI channel connector, on the rear of your server, to
connect different types of small computer system interface (SCSI) devices. Inside the
server, a SCSI cable connects the internal SCSI channel connector to the hot-swap
drive backplane.
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 system-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 your 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
Table 13. Auxiliary-device connector pin-number assignments .
Pin Signal
1 Data
2 Not connected
3 Ground
4 +5 V dc
5 Clock
6 Not connected