HP-UX System Administrator's Guide: Overview

Mass Storage Hardware Paths (three formats)
Hardware paths, as the name implies, define the physical paths that data travels to
reach devices. In HP-UX 11i version 3 there are three formats to specific hardware paths
to mass storage devices.
Legacy Hardware Paths
This is the format used in releases prior to HP-UX 11i Version 3. It is composed of a
series of bus-nexus addresses separated by slash characters (“/”) leading to the host
bus adapter (HBA); beneath the HBA, additional address elements are separated by
periods (“.”).
For directly connected devices, the addressing can be a simple target and LUN:
0/0/2/0.1.7.0
For SCSI-3 devices connected through a storage area network (SAN), legacy addressing
is emulated with a domain, area, port, virtual bus, virtual target, and
virtual LUN:
0/2/1/0.1.5.0.0.3.7
Lunpath Hardware Paths
This format is used for addressing LUNs in agile mode. It is identical to the legacy
hardware path format up to the host bus adapter (HBA). Beneath the HBA, two
additional address elements are represented (in hexadecimal):
Target address A transport dependent address identifying the physical device
associated with the hardware path
LUN address A 64-bit representation of the LUN identifier reported by the
target.
0/2/1/0.0x50001fe1500170ac.0x4017000000000000 is an example of a SCSI-3
hardware path.
Figure 3-4 Lunpath Hardware Path Components
HBA Path
0/2/1/0.0x50001fe1500170ac.0x4017000000000000
Target Address LUN Address
LUN Hardware Paths
Because devices can have multiple physical hardware paths, a virtualized LUN hardware
path is needed so that the hardware path that a persistent device special file maps to
remains the same even when the underlying physical hardware path elements change.
66 Major Components of HP-UX