Digital Equipment VAX 4000 108, Информация пользователя

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Programming Parameters for DSSI Devices
VAX 4000 Model 108 User Information E-3
Refer to the DSSI VMScluster guide for rules for specifying allocation class values.
The UNITNUM parameter determines the unit number of the device. By default, the
device unit number is supplied by the jumpers on the drives. Systems with multiple DSSI
busses, as described later in this section, require that the default values be replaced with
unique unit numbers. To set unit numbers and override the default values, you use the
console-based DUP driver utility to supply values to the UNITNUM parameter and to set a
value of zero to device parameter FORCEUNI.
The FORCEUNI parameter controls the use of UNITNUM to override the default device
unit number supplied by the jumpers. When FORCEUNI is set to a value of zero, the
operating system uses the value assigned to the UNITNUM parameter; when FORCEUNI
is set to a value of one, the operating system uses the value supplied by the jumpers.
The NODENAME parameter allows each device to have an alphanumeric node name of
up to eight characters. DSSI devices are shipped from the factory with a unique identifier,
such as R7CZZC, R7ALUC, and so on. You can provide your own node name.
The SYSTEMID parameter provides a number that uniquely identifies the device to the
operating system. That parameter may need to be modified only when replacing a device.
Only Digital service representatives and licensed self-maintenance customers should
remove devices.
How VMS Uses the DSSI Device Parameters
This section describes how the operating system uses the parameters to form unique
identifiers for each device. Configurations that require you to assign new unit numbers for
devices are also described.
With an allocation class of zero, the operating system can use the default parameter values
to provide each device with a unique device name. The operating system uses the node
name along with the device logical name in the following manner.
NODENAME$DIAu
where NODENAME is a unique node name, and u is the unit number.
With a nonzero allocation class, the operating system relies on unit number values to
create a unique device name. The operating system uses the allocation class along with the
device logical name in the following manner.
$ALLCLASS$DIAu
where ALLCLASS is the allocation class for the system and devices, and
u is a unique unit number.