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v Domain-name validation to negotiate compatible data-transfer speeds with each
device
v Cyclic redundancy checking (CRC), instead of the usual parity checking, to
improve data reliability
v An active terminator for SCSI bus termination
The server comes with one SCSI cable, which connects the internal connector on
the system board to the standard hot-swap-drive backplane. If you plan to attach
external SCSI devices, you must order additional cables. To select and order the
correct cables for use with external devices, contact your IBM marketing
representative or authorized reseller.
SCSI cabling requirements
For information about the maximum length of SCSI cable, go to the American
National Standards Institute (ANSI) SCSI standards on the ANSI Web site at
http://www.ansi.org/. Adhering to these standards will help to ensure that the server
operates properly.
SCSI IDs
Each SCSI device that is 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. Table 5 lists the SCSI IDs for the hard disk drives and
backplanes that are connected to one channel.
Table 5. SCSI IDs for standard hot-swap hard disk drives, controller, and backplane
Device
Drive bay 1
Drive bay 2
Drive bay 3
Drive bay 4
Drive bay 5
Drive bay 6
Controller
Backplane
The hot-swap-drive backplane controls the SCSI IDs for the internal hot-swap drive
bays. However, when you attach an external SCSI device to an optional SCSI
adapter, you must set a unique ID for the device. See the information that comes
with the device for instructions for setting its SCSI ID.
SCSI connector
The following illustration shows a SCSI connector.
1
34
35
68
SCSI ID
0
1
2
3
4
5
7
8
Chapter 3. Installing options
45
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Troubleshooting
