AB378B Fibre Channel Mass Storage Adapter Installation Guide, December 2006

Fibre Channel Adapter Installation for HP-UX

Interpreting Hardware Paths

Chapter 1

LUN Addressing Method Value of LUN field in Fibre Channel hardwarePath.

Peripheral Device Addressing The Target or LUN field of the Logical Unit Number.

Logical Unit Addressing The LUN field of the Logical Unit Number.

Volume Set Addressing

(Flat Space Addressing) Bits 0 - 2 of the Logical Unit Number.

For more information about the fields in the Logical Unit Number, please see the SCSI Architecture Model - 3

(SAM-3) standards document.

Fibre Channel devices can connect to a fabric using either Direct Fabric Attach or Public Loop. Different

devices can have different types of connections to the same fabric; for example, an HBA can have a Direct

Fabric Attach connection to the fabric, while an array has a Public Loop connection to the same fabric.

Public Loop devices have an Arbitrated Loop Physical Address (AL_PA). The AL_PA usually appears in the

least significant byte of the device's N_Port ID. Direct Fabric Attach devices do not have an AL_PA and the

least significant byte of their N_Port ID is usually 0. This is dependent on the switch implementation. Not all

switches adhere to this scheme.

Some switches enable devices in Private Loop mode to connect to a fabric. These switches typically translate

the Private Loop device as either a Public Loop or Direct Fabric Attach device to the rest of the fabric. These

switches also typically translate the rest of the fabric as Private Loop devices to the Private Loop device.

Target Depends on the

Fibre Channel

topology and the

LUN addressing

method used.

For LUNs with Peripheral Device

Addressing, the value of this field is

the lower 4-bits of the third byte of

the N_Port ID of the target device.

This field usually corresponds to the

Arbitrated Loop Physical Address

(AL_PA) of the target device.

With Peripheral Device

Addressing, the value of this field

is the lower 4-bits of the Loop ID

of the target device.

For LUNs with Logical Unit Addressing,

the value is the Target field of the LUN.

For LUNs with Volume Set Addressing (Flat Space Addressing),

the value is bits 3 - 6 of the LUN.

LUN Depends only on the LUN addressing method used.

Table 1-4 Hardware Path Field Descriptions (Continued)

Field Value

Fibre Channel Topology of HBA

Fabric Topologies Private Loop