HP StorageWorks HSG80 ACS Solution Software V8.8 for Tru64 UNIX Installation and Configuration Guide (AA-RV1VA-TE, March 2005)

Planning a Subsystem
48 HSG80 ACS Solution Software V8.8 for Tru64 UNIX Installation and Configuration Guide
StorageWorks recommends 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 3 summarizes the recommendations for unit assignments based on the
SCSI_VERSION switch.
What is 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.
The default condition is ENABLE_ACCESS_PATH=ALL. This specifies that
access paths to ALL hosts are enabled. HP recommends that you restrict host
access and that the access path be carefully specified to avoid providing undesired
host connections access to the unit.
Now with V88, you may change the default subsystem behavior so that units are
always created without enabling connections. This provides more control in
granting appropriate access to specific connections.
Table 3: 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