HP StorageWorks HSG80 ACS Solution Software V8.8 for IBM AIX Installation and Configuration Guide (AA-RV1HA-TE, March 2005)

Planning a Subsystem
51HSG80 ACS Solution Software V8.8 for IBM AIX Installation and Configuration Guide
What is Selective Storage Presentation?
Selective Storage presentation is a feature of the HSG80 controller that enables
you 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 V8.8-1 you may change the subsystem behavior so that units are always
created without enabling connections. This provides more control in granting
appropriate access to specific connections.
The command syntax to disable is:
HSG> SET this/other Default_Access=Disable
The command syntax to enable is:
HSG> SET Default this/other Default_Access=Enable (default after
upgrade)
When the command is invoked from one controller, the Default_Access from the
other controller will be similarly modified. The setting is symmetrical and
persistent across restarts, FRUTIL, etc.
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