HSG80 ACS Solution Software Version 8.7 for Compaq Tru64 UNIX Installation and Configuration Guide

Planning a Subsystem
1–26 HSG80 ACS Solution Software Version 8.7 for Compaq Tru64 UNIX Installation and
Configuration Guide
For example:
Figure 1–14 shows a representative multiple-bus failover configuration. Restricting
the access of unit D101 to host BLUE can be done by enabling only the connections to
host BLUE. At least two connections must be enabled for multiple-bus failover to
work. For most operating systems, it is desirable to have all connections to the host
enabled. To enable all connections for host BLUE, enter the following commands:
SET D101 DISABLE_ACCESS_PATH=ALL
SET D101 ENABLE_ACCESS_PATH=BLUE1A1,BLUE1B1,BLUE2A2,BLUE2B2
To enable only two connections for host BLUE (if it is a restriction of the operating
system), select two connections that use different adapters, different switches or hubs,
and different controllers:
SET D101 DISABLE_ACCESS_PATH=ALL
SET D101 ENABLE_ACCESS_PATH=(BLUE1A1, BLUE2B2)
or
SET D101 DISABLE_ACCESS_PATH=ALL
SET D101 ENABLE_ACCESS_PATH=(BLUE1B1, BLUE2A2)
If the storage subsystem has more than one host connection, the access path must be
specified carefully to avoid giving undesirable host connections access to the unit. The
default condition for a unit is that access paths to all host connections are enabled. To
restrict host access to a set of host connections, specify
DISABLE_ACCESS_PATH=ALL when the unit is added, then use the
SET unit
command to specify the set of host connections that are to have access to the unit.
Enabling the access path to a particular host connection does not override previously
enabled access paths. All access paths previously enabled are still valid; the new host
connection is simply added to the list of connections that can access the unit.
IMPORTANT: The procedure of restricting access by enabling all access paths then disabling
selected paths is not recommended because of the potential data/security breach that occurs
when a new host connection is added.
Restricting Host Access by Offsets
Offsets establish the start of the range of units that a host connection can access.
However, depending on the operating system, hosts that have lower offsets may be
able to access the units in the specified range.
NOTE: All host connections to the same host computer must be set to the same offset.