DEC 4000 600 series, Руководство пользователя, Страница: 167 / 242

Setting and Examining Parameters for DSSI Devices
DSSI Device
Parameter
Descriptions
Drive ID
The drive ID parameter is provided by the drive ID plug on the
front panel of the storage compartment. Each DSSI bus can
support up to eight devices, (drive IDs 0–7). Each DSSI adapter
and each device count as a node. Hence, in a single-system
configuration, a DSSI bus can support up to seven devices, drive
IDs 0–6 (with drive ID 7 reserved for the adapter).
ALLCLASS
The ALLCLASS parameter determines the device allocation
class. The allocation class is a numeric value from 0–255 that
is used by the OpenVMS AXP operating system to derive a
path-independent name for multiple access paths to the same
device. The ALLCLASS parameter corresponds to the OpenVMS
AXP IOGEN parameter ALLOCLASS.
DSSI devices are shipped from the factory with a default
allocation class of zero. Each device to be served to a cluster
must have a nonzero allocation class that matches the allocation
class of the system. Refer to the VMS VAXcluster Manual for
rules on specifying allocation class values.
UNITNUM
The UNITNUM parameter determines the unit number of the
device. By default, the device unit number is supplied by the
drive ID plug on the front panel of the storage compartment.
Systems using multiple DSSI buses, 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
cdp console command to supply values to the
UNITNUM parameter.
NODENAME
The NODENAME parameter allows each device to have an
alphanumeric node name of up to six 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.
SYSTEMID
The SYSTEMID parameter provides a number that uniquely
identifies the device to the operating system.
System Configuration 6–27