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Before configuring your subsystem, you must first understand the basic
SCSI concepts so that your subsystem and SCSI devices will function
properly.
4.1 SCSI IDs
A SCSI ID is an identifier assigned to SCSI devices that enables them to
communicate with a computer when they are attached to a host adapter
via the SCSI bus. Each SCSI device, and the host adapter itself, must
have a SCSI ID number (Fast SCSI-2 = 0 to 7, Ultra Wide SCSI = 0-15).
The ID will define each SCSI device on the SCSI bus. If there are more
than one SCSI adapter in the Host subsystem, each adapter forms a
separate SCSI bus. SCSI IDs can be reused as long as the ID is as-
signed to a device on a separate SCSI bus. Refer to the documentation
that came with your peripheral device to determine the ID and how to
change it.
Note:
4.2 Terminators
Based on SCSI specification, SCSI bus must be terminated at both ends.
Meaning, the devices that are connected to the ends of the SCSI bus
must have their bus terminators enabled. Devices connected in the
middle of the SCSI bus must have their terminators disabled. Proper
termination allows data and SCSI commands to be transmitted reliably
on the SCSI bus. Your host adapter and the SCSI devices attached to it
must be properly terminated, or they will not work reliably.
Termination means that terminators are installed in the devices at each
end of the bus. Some SCSI devices would require you to manually insert
or remove the terminators. Other devices have built-in terminators that
are enabled or disabled via switches or software commands. Refer to
your device's documentation on how to enable or disable termination.
SCSI IDs has nothing to do with the order in which
devices are cabled to the host adapter.
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