HSG80 ACS Solution Software V8.6 for Windows NT and Windows 2000 Installation and Configuration Guide

1–28 HSG80 ACS Solution Software Version 8.6 for Windows NT and Windows 2000 Installation and
Configuration Guide
NOTE: All host connections to the same host computer must be set to the same offset.
For example:
In Figure 1–14, assume all host connections initially have the default offset of 0. Giving
all connections access to host BLUE, an offset of 120 will present unit D120 to host
BLUE as LUN 0. Enter the following commands:
SET BLUE1A1 UNIT_OFFSET=120
SET BLUE1B1 UNIT_OFFSET=120
SET BLUE2A2 UNIT_OFFSET=120
SET BLUE2B2 UNIT_OFFSET=120
Host BLUE cannot see units lower than its offset, so it cannot access any other units.
However, the other two hosts can still access D120 as LUN 20 if their operating system
permits. To restrict access of D120 to only host BLUE, enable only host BLUE’s access,
as follows:
SET D120 DISABLE_ACCESS_PATH=ALL
SET D120 ENABLE_ACCESS_PATH=(BLUE1A1,BLUE1B1,BLUE12A2,BLUE2B2)
NOTE: Compaq recommends that you always provide access to only specific connections. This
way, if new connections are added, they will not have automatic access to all units. See
“Restricting Host Access by Disabling Access Paths,” page 1–24.
Worldwide Names (Node IDs and Port IDs)
A worldwide name—also called a node ID—is a unique, 64-bit number assigned to a
subsystem prior to shipping. The node ID belongs to the subsystem itself and never
changes.
Each subsystem’s node ID ends in zero, for example 5000-1FE1-FF0C-EE00. The
controller port IDs are derived from the node ID.
In a subsystem with two controllers in transparent failover mode, the controller port IDs
are incremented as follows:
■ Controller A and controller B, port 1—worldwide name + 1, for example
5000-1FE1-FF0C-EE01
■ Controller A and controller B, port 2—worldwide name + 2, for example
5000-1FE1-FF0C-EE02
In multiple-bus failover mode, each of the host ports has its own port ID: