Configuring a Device
Using the Generic Class Driver
On
VAX systems, the System Generation utility (SYSGEN) loads the generic
SCSI class driver into system virtual memory, creates additional
data structures for the device unit, and calls the driver's controller initialization
routine and unit initialization routine. SYSGEN automatically loads
and autoconfigures the SCSI port driver at system initialization.
As part of autoconfiguration, SYSGEN polls each device on each SCSI
bus. If the device identifies itself as a direct-access device,
direct-access CD-ROM device, or flexible disk device, SYSGEN automatically
loads the disk class driver (DKDRIVER). If the device identifies
itself as a sequential-access device, SYSGEN automatically loads
the tape class driver (MKDRIVER). If the autoconfiguration facility
does not recognize the type of the SCSI device, it does not load
a driver.
If a third-party-supplied SCSI device requires that the generic
class driver be loaded, it must be configured by an explicit SYSGEN
CONNECT command, as follows:
$ RUN SYS$SYSTEM:SYSGEN SYSGEN> CONNECT GKpd0u /NOADAPTER
On Alpha systems, SYSMAN performs the same functions that
SYSGEN performs on VAX systems. If a third-party-supplied SCSI device
requires that the generic class driver be loaded, the device must
be configured by an explicit SYSMAN CONNECT command, as follows:
$ RUN SYS$SYSTEM:SYSMAN SYSMAN> IO CONNECT GKpd0u /NOADAPTER/DRIVER=SYS$GKDRIVER
On VAX and Alpha systems, GK is the device
mnemonic for the generic SCSI class driver (GKDRIVER); p represents
the SCSI port ID (for instance, the controller ID A or B ); d represents
the SCSI device ID (a digit from 0 to 7); 0 signifies the digit
zero; and u represents the SCSI logical unit
number (a digit from 0 to 7).
Multiple devices residing on any SCSI bus in the system can
share GKDRIVER as a class driver, as long as a CONNECT command is
issued for each target device that requires the driver.
Because just one connection can exist through the SCSI port
driver to each target, the generic class driver cannot be used for
a target if a different SCSI class driver is already connected to
that target. For example, if the SCSI disk class driver has a connection
to device ID 2 on the SCSI bus identified by SCSI port ID B (DKB200),
the generic class driver cannot be used to communicate with this
disk. An attempt to connect GKDRIVER for this target results in
GKB200 being placed off line.
Disabling the Autoconfiguration of a SCSI
Device (VAX Only) On
VAX systems, in special cases you may need to prevent the autoconfiguration
facility from loading the disk or tape class driver for a device
with a specific port ID and device ID. This would be the case if
a SCSI device, supplied by a source other than HP, should identify
itself as either a random-access or sequential-access device and
were to be controlled by the generic SCSI class driver.
To disable the loading of a disk or tape driver for any given
device ID, OpenVMS defines the special system parameter SCSI_NOAUTO.
The SCSI_NOAUTO system
parameter, as shown in
SCSI_NOAUTO System Parameter, stores a bit mask of 32 bits in which the low-order byte
corresponds to the first SCSI bus (PKA0), the second byte corresponds
to the second SCSI bus (PKB0), and so on. For each SCSI bus, setting
the low-order bit inhibits automatic configuration of the device with
SCSI device ID 0; setting the second low-order bit inhibits automatic
configuration of the device with SCSI device ID 1, and so forth.
For instance, the value 0000200016 would
prevent the device with SCSI ID 5 on the bus identified by SCSI
port ID B from being configured. By default,
all of the bits in the mask are cleared, allowing all devices to
be configured.
HP OpenVMS I/O User's Reference Manual
Using the OpenVMS Generic SCSI Class Driver
