Data General AViiON 5500 Series, Установка, расширение и обслуживание

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Planning a SCSI bus configuration
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Planning a SCSI bus configuration
You should carefully plan your entire SCSI bus configuration before
you begin setting up the devices. Make sure that your system
adheres to the SCSI device identification, cable, and bus
termination rules given in this section.
Use the worksheets at the end of this chapter (Figure 3–6 provides
a sample) along with the information in the following sections, to
plan and/or verify your configuration.
Once you have verified your configuration, continue with the later
section, “Connecting external SCSI drives and storage subsystems.”
Determining SCSI bus speed
The SCSI bus operates at
FAST
or
SLOW
speed. To use
single–ended external devices, the default speed of the SCSI bus in
your system must be
SLOW
.
You view or set the SCSI bus speed using an SCM (System Control
Monitor) configuration menu. Refer to the manual Operating
AViiON 5500 and 550 Series Computers for instructions.
Calculating SCSI bus cable lengths
Cabling for a SCSI bus begins at the SCSI controller; it connects all
mass–storage drives on the bus in a cabled series of links known as
a “daisy–chain” configuration.
Consider the following when you calculate the total length of your
SCSI bus cabling:
D
A singled–ended bus cannot exceed 6 meters (~19.6 feet).
D
A differential bus cannot exceed 25 meters (~82.2 feet).
Integrated SCSI controller
The internal SCSI controller is set by default for singled–ended
operation; therefore, the total bus length cannot exceed 6 meters
(19.6 feet).
1.25 meters (4.1 feet) of the cable maximum resides within the
AViiON 5500 or 550 series computer unit. Thus, the external
connector for the integrated SCSI controller supports up to
4.75 meters (15.6 feet) additional bus length.