HP-UX Installation

Interpreting Hardware Paths

 

 

 

 

 

 

 

Fibre Channel Topology of HBA

Field

 

Value Information

Fabric Topologies such as Public

 

Private Loop

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Loop and Direct Fabric Attach

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Target

 

The value depends

For LUNs with Peripheral Device

With Peripheral Device

 

 

on both the Fibre

Addressing, the value of this field is

Addressing, the value of this field

 

 

Channel topology

the lower 4-bits of the third byte of

is the lower 4-bits of the Loop ID

 

 

and the LUN

the N_Port ID of the target

of the target device.

 

 

addressing method

device.

 

 

 

 

 

used.

 

This field usually corresponds to the

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Arbitrated Loop Physical Address

 

 

 

 

 

 

 

 

(AL_PA) of the target device.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

For LUNs with Logical Unit Addressing, the value is the Target field of

 

 

 

 

 

 

the Logical Unit Number.

 

 

 

 

 

 

 

 

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

 

 

 

 

 

 

value is bits 3 - 6 of the Logical Unit Number.

 

 

 

 

 

 

 

 

LUN

 

The value of this field depends only on the LUN addressing method used, see below.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LUN

 

 

 

Peripheral Device

 

 

Volume Set Addressing
Addressing

 

Logical Unit Addressing

 

Addressing

(Flat Space Addressing)
Method

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Value of LUN

The Target or LUN field of

The LUN field of the

 

Bits 0 - 2 of the Logical Unit

field in FC

 

 

 

the Logical Unit Number.

Logical Unit Number.

 

Number.

HW Path

 

 

 

 

 

 

 

 

 

 

 

 

For more information about the fields in the Logical Unit Number, please refer to the SCSI Architecture

Model - 3 (SAM-3) standards document.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NOTE

 

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

 

 

 

Different devices may have different types of connections to the same Fabric, for example an

 

 

 

HBA may have a Direct Fabric Attach connection to the Fabric, while an array has a Public

 

 

 

Loop connection to the same Fabric. In other words, in a Fabric, the Fibre Channel Topology of

 

 

 

an HBA may be different from the Fibre Channel Topology of devices seen by that HBA.

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 and not all switches adhere to this scheme.

Some switches allow devices in Private Loop mode to connect to a Fabric. In these situations, the switch typically translates the private loop device as either a Public Loop or Direct Fabric Attach device to the rest of the Fabric. The switch also typically translates the rest of the Fabric as Private Loop devices to the Private Loop device.

Chapter 1

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