HP Fibre Channel Fabric Migration Guide

17
Fabric Migration Guide
Fabric Device Addressing Changes
Device Addressing in a Fabric Environment
HP’s current model of addressing associates devices with their hardware
path information. In the case of Fibre Channel disk devices, the device
file names are little more than tags that are associated with a node in the
system iotree. Using the ioscan command, ioscan -kfn -C disk, you
can obtain this association.
During the kernel initialization phase of the boot process, ioscan scans
the hardware I/O subsystem for attached devices, and builds an iotree.
Any new devices that are found during this scan process will have new
device files created for them.
The current Fibre Channel implementation over a Private Arbitrated
Loop uses the Hard Physical Address (HPA) of the FC target to generate
a portion of the hardware path to the Fibre Channel port. Behind this
port, virtual SCSI buses, targets and LUNs will exist.
In a fabric environment, the N_Port address is used to generate this
portion of the hardware path to the Fibre Channel port. Behind this port,
virtual SCSI buses, targets, and LUNs exist in the same manner as the
existing configurations. The fabric/switch is responsible for the
generation of the N_Port address. Three fields comprise this address:
Domain Generally associated with the physical instance of a
switch. (To determine how the domain is assigned on a
particular switch, refer to that switch vendor’s
documentation.)
Area Generally associated with a port on the switch.
Port Set to 0 for direct fabric attached devices (N_Port to
F_Port).
Set to the AL_PA associated with the Hard Physical
Address or loop identifier of a Fibre Channel target for
public loop devices. (See the FC-AL-2 annex K for this
mapping. Figure 0-6 shows an example of the annex K
table).
For private loop devices, the port field(s) in the HW
path in an ioscan output contains the Hard Physical
Address or loop identifier of the target device.