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

1–22 HSG80 ACS Solution Software Version 8.6 for Windows NT and Windows 2000 Installation and
Configuration Guide
Table 1–1 summarizes the recommendations for unit assignments based on the
SCSI_VERSION switch.
Selective Storage Presentation
Selective Storage presentation is a feature of the HSG80 controller that enables the user to
control the allocation of storage space and shared access to storage across multiple hosts.
This is also known as Restricting Host Access.
In a subsystem that is attached to more than one host or if the hosts have more than one
adapter, it is possible to reserve certain units for the exclusive use of certain host
connections.
For a controller pair, the method used to restrict host access depends on whether the
controllers are in transparent or multiple-bus failover mode. For a single controller, the
methods are the same as for a controller pair in transparent failover.
NOTE: The default condition is ENABLE_ACCESS_PATH=ALL. This specifies that access paths
to ALL hosts are enabled. It is recommended that the user restrict host access and that the
access path be carefully specified to avoid providing undesired host connections access to the
unit.
Restricting Host Access in Transparent Failover Mode
Three methods can be used to restrict host access to storage units in transparent failover
mode:
■ Using separate Fibre Channel links (either loop or fabric)
■ Enabling the access path of selected host connections on a shared loop or fabric
■ Setting offsets
NOTE: These techniques also work for a single controller.
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