IBM PC Server 325, User Handbook Manual

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Working with Internal Drives
The internal SCSI cable is attached to the CD-ROM drive, any
preinstalled hard disk drives, and the SCSI connector on the system
board. You can attach additional SCSI devices to this cable.
SCSI IDs
If you install additional SCSI devices, you must set a unique
identification (ID) for each SCSI device that you connect to your
server. This enables the SCSI controller to identify the devices and
ensure that different devices do not attempt to transfer data at the
same time.
The SCSI controller in your server supports SCSI IDs 0 to 15; ID 7 is
reserved for the controller. Use SCSISelect to view the SCSI IDs of
SCSI devices in your server. (See “Using the SCSISelect Utility
Program” on page 47 for more information.)
If you install wide (16-bit) SCSI devices, you can set the IDs to any
whole number between 8 and 15. If you install narrow (8-bit) SCSI
devices, you can set the IDs to any whole number between 0 and 6.
Termination Requirements
The devices at both ends of the SCSI bus must be terminated. If
you attach SCSI devices (internal or external), you must terminate
the last device in the chain. A special connector, called a terminator,
is used to terminate a SCSI chain.
Refer to the instructions that come with the SCSI devices for
information about setting a SCSI ID.
If you have only internal SCSI devices connected to the internal
SCSI controller and the external SCSI cable has not been installed,
the controller becomes the termination at one end of the cable.
If you attach internal SCSI devices to the SCSI controller in your
server, you must terminate the last internal device on the bus (cable)
and disable the termination on the other devices connected to the
SCSI connector. The SCSI bus on the system board is already
terminated.
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PC Server 325 User's Handbook