HP-UX Mass Storage Stack - Hardware Path Aliasing

New scsimgr attributes

The following scsimgr attributes were introduced in the initial release of the hardware path aliasing

feature:

• hwp_abs_alias

• hwp_comp_alias

These new attributes are applicable for HBA, target path, lunpath, and LUN objects. Similar to

existing scsimgr attributes, these attributes are managed with the scsimgr get_attr, set_attr,

and save_attr commands. By default, these attributes values are set to NULL strings.

Beginning with the HP-UX 11i v3 March 2011 release, there is a new global attribute to control

whether to use the default hardware path aliasing scheme: hwp_alias_enable. This attribute is set

to true (1) by default. By using the default hardware path aliasing scheme, you can avoid manually

setting hwp_abs_alias and hwp_comp_alias values.

Valid hardware path alias names

The rules for hardware path alias names are as follows:

• Must begin with an alphabetical character, but may contain any alphanumeric character

• Absolute aliases can have a maximum of 128 characters

• Component aliases can have a maximum of 64 characters

• May not contain special characters other than a dash (-) and underscore (_)

• Must be unique, although an absolute alias and component alias may be identical

• Must not conflict with a default alias path.

Default hardware path aliasing scheme

To simplify management of hardware path aliases, the HP-UX 11i v3 March 2011 release implements

a default scheme that sets default hardware path aliases for objects as they register during the boot

process. The scheme builds on top of the existing hwp_abs_alias and hwp_comp_alias attributes

so the saved values for these attributes are maintained. The following rules are applied (in order) for

each type of storage object. If one of the saved attribute values is found, the remaining rules are not

considered. If the attribute value is not a valid hardware path alias, no default HPA is assigned for

that object (it remains NULL).

For all object types, if the hardware path alias determined by the default scheme conflicts with an

alias already in use (that is, a saved hwp_abs_alias, hwp_comp_alias, tport_alias, or LUN alias

value conflicts with an alias created with the default scheme), the first object to register is assigned the

given hardware path alias. Precedence is neither given to the alias created with the default scheme

nor the user defined alias, but to the object that registers a given alias path first. The alias of the other

object that is assigned the same hardware path alias (either user defined or default) is set to NULL.

For example, if an interface card is claimed by the mpt driver, the alias path created with the default

scheme is as follows:

Class instance hwpath alias

ext_bus 0 0/0/0/0 mpt0

Then, set a user-defined alias path to mpt0 as follows: