HSG80 ACS Solution Software V8.6 for Compaq OpenVMS Installation and Configuration Guide

1–14 HSG80 ACS Solution Software Version 8.6 for Compaq OpenVMS Installation and Configuration Guide
It is recommended to use the following conventions when assigning host connection
offsets and unit numbers in SCSI-2 mode:
■ Offsets should be divisible by 10 (for consistency and simplicity).
■ Unit numbers should be assigned at connection offsets (so that every host connection
has a unit presented at LUN 0).
Table 1–1 summarizes the recommendations for unit assignments based on the
SCSI_VERSION switch.
Assigning Unit Identifiers
One step is required when configuring storage units for specifying an identifier (or LUN
ID alias) for each unit. A unique identifier is required for each unit (virtual disk). This
identifier must be unique in the cluster.
This section gives two examples of setting an identifier for a previously created unit: one
using CLI and one using SWCC. The CLI uses the older terms “identifier” and “unit”,
while SWCC uses the terms “LUN ID alias” and “virtual disk”.
Identifier = LUN ID alias
Unit = virtual disk
Using CLI to Specify Identifier for a Unit
The command syntax for setting the identifier for a previously created unit (virtual disk)
follows:
SET UNIT_NUMBER IDENTIFIER=NN
NOTE: It is strongly suggested that, for simplicity, the identifier match the unit number. For
example, to set an identifier of 97 for unit D97, use the following command:
SET D97 IDENTIFIER=97
Table 1–1 Unit Assignments and SCSI_VERSION
SCSI_VERSION Offset Unit Assignment What the connection sees LUN 0 as
SCSI-2 Divisible by 10 At offsets Unit whose number matches offset
SCSI-3 Divisible by 10 Not at offsets CCL