Data General AViiON 530 Series, Клиентская документация, Страница: 75 / 266

Setting Up and Installing a SCSI Bus
014–002091
4-7
Configuring Device Operating Parameters
The SCSI devices you received with your system are preconfigured to comply with the
operating parameters of the controller and the other drives on the SCSI bus. Before
you install an internal or external device on your SCSI bus, you need to set its
operating parameters as described in this section. Configure all new or replacement
drives as follows:
•
Set all disk drives for sequential drive motor start. The drive will then delay
starting up its spindle motor a number of seconds (a multiple of the SCSI ID
number) when you power up your system.
• Set all drives so that the SCSI bus (host system) provides terminator power rather
than the drives themselves. Some devices specify this option as SCSI pin 26 ON,"
or power from interface cable pin 26."
•
Set any drive that offers these options to enable parity checking and arbitration.
•
Make sure the bus termination is correct on the new drive:
In an AViiON 530 or 4600 series computer or mass-storage subsystem,
all drives
and SCSI adapter boards must have their SCSI bus terminator resistors removed .
Most stand-alone drives employ an external terminator plug to terminate the SCSI
bus; if your drive does
not have an external terminator, and will be physically
positioned as the last drive on the SCSI bus, you must install bus termination
resistors. Refer to the next section, Terminating the External SCSI Bus."
NOTE: For information about setting the SCSI jumpers/switches and removing the
terminator resistors, refer to the list of drive installation manuals in the
Guide to AViiON

and DG/UX

System Documentation .
Terminating the External SCSI Bus
You must terminate the SCSI bus at the last device or peripheral housing unit on each
SCSI bus (SCSI A and SCSI B). Depending on the physical placement and type of
SCSI peripherals included in your system, you terminate your bus with one of the
following:
•
A terminating plug that you install on the unused bulkhead connector on the
outside of the unit. On such housings (for example, the Model 10565 Mass Storage
Subsystem), do not terminate any of the SCSI devices within the unit.
•
A terminating resistor pack that you install on an individual drive's printedĆcircuit
board. Note that devices terminated in this manner must also connect at the
physical
end of any daisy-chain configuration.
To locate the SCSI bus terminators and connectors for each SCSI drive and drive
housing in your system, refer to the device-specific manual for that drive or unit.