User`s guide

The xxx number determines the SCSI host side bus number and the SCSI target
ID. The LUN is assumed to be 0 in all cases. The calculations are as follows:
SCSI host side bus number = Integer of ( xxx / 8 )
The remainder of the above division, if any, is the target ID.
MAKEDEV calculates the minor number, based upon the same calculation used
in the previous examples, except that the LUN is always 0:
Example 8–12 How MAKEDEV Calculates the Minor Number
(16384 * SCSI Host Bus # ) + (Target ID * 1024) + (LUN * 64) + Partition
Using a unit name of RZ16 = 16 is the xxx
SCSI host side bus number = ( 16 / 8 ) = 2 with a remainder of 0.
Minor number for rz16a = ( 16384 * 2 ) + ( 0 * 1024 ) + ( 0 * 64 ) + 0 = 32768
MAKEDEV then invokes the mknod utility using the major number associated
with that device type and the calculated minor number. It creates all special files
for all partitions, both block mode and character mode.
If a DEC OSF/1 device name of rz16 was used, what HSZ40 unit would
MAKEDEV assume? Remember that an HSZ40 unit has the designator DTZL:
T = Target ID
Z=0
L = LUN
Remember that rz16 was on SCSI host side bus number 2, target ID 0, and a
LUN of 0.
The rz16 device would relate to HSZ40 UNIT D000 or D0 that is connected to the
host adapter on SCSI host side bus number 2.
If the MAKEDEV utility is used to create special files, give the device a DEC
OSF/1 device-name that will produce the correct minor number. Remember,
MAKEDEV cannot be used to create special files for HSZ40 units whose unit
designators do not end in zero (0). For example, MAKEDEV cannot be used for
HSZ40 unit D101. This would be target ID 1, but LUN 1. MAKEDEV always
assumes LUN to be zero (0).
When using the MAKEDEV utility, the current working directory should be
/dev. To invoke the MAKEDEV utility enter the following command (this is an
example):
/dev/MAKEDEV rz16
As another example, if a device name of rz161 was chosen and MAKEDEV is
used to create the special files. What HSZ40 unit would MAKEDEV assume?
SCSI host side bus number = ( 161 / 8 ) = 20 with a remainder of 1
The Target ID is then equal to this remainder, which is 1.
LUN is always 0, so using the DTZL HSZ40 unit designator formatting scheme,
this would be D100 on the HSZ40 on the host adapter on Host
Side SCSI bus 20.
Operating System Support 8–37