HP Fibre Channel Mass Storage Adapters Support Guide FibrChanl-02 (fclp) Driver, September 2009

Table 2-3 Hardware Path Field Descriptions (continued)
Fibre Channel Topology of HBA
ValueField
Private LoopFabric Topologies
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 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.
Depends on the Fibre
Channel topology and
the LUN addressing
method used.
Target
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.
Depends only on the LUN addressing method used.LUN
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.
Interpreting Hardware Paths 17