Lunpath hardware paths are a new representation of hardware
paths introduced on HP-UX 11i v3, as part of the new agile representation
of mass storage devices. For more details, please refer to the Next
Generation Mass Storage Stack HP-UX 11i v3 white paper
at http://docs.hp.com/en/netsys.html#Storage%20Area%20Management .
This section describes how to interpret address elements in
lunpath hardware paths. It also shows how to map between the legacy
hardware path and lunpath hardware path formats.
Fibre Channel |
 |
The target address for a Fibre Channel
device is the target port’s worldwide port name (WWPN).
The fcmsutil command with the get remote option displays the WWPN as the Target Port World Wide
Name. In this example, the WWPN is 0x500805f300083899:
# fcmsutil /dev/td0 get remote all Target N_Port_id is = 0x010700 Target state = DVS_READY Symbolic Name = Port Type = N_PORT SLER Capable (supports Retry & TRID) = NO Target Port World Wide Name = 0x500805f300083899 Target Node World Wide Name = 0x500805f300083890 |
The LUN address for a Fibre Channel device
is a 64-bit LUNid. The LUNid is composed of two bits representing
the addressing method, fourteen bits representing the LUN number
of the device, and 48 reserved bits, as shown in the table:
Table 1-5 Title not available (Fibre Channel)
| Addressing Method(2 bits) | LUN Number(14 bits) | Reserved(48 bits) |
|---|
| 00 - Peripheral Device Addressing01 - Volume
Set Addressing (Flat Space Addressing)10 - Logical Unit
Addressing | 0x00-0x3fff | 0x00 |
Since the LUN address is printed in hexadecimal, the first
hexadecimal digit contains both the addressing method and the start
of the LUN number. For example, the first 16 bits of the LUN address
0x400f000000000000 is binary 0100000000001111. The leading 01
is theaddressing method (Flat Space Addressing ) and the remaining
bits represent the LUN number (15). Thus, the LUN address 0x400f000000000000
represents LUN number 15, using the Flat Space Addressing method.
You can easily perform this decoding by using the scsimgr command to display the LUN’s lunid attribute. For example:
# scsimgr get_attr -H 0/2/1/0.0x500805f300083899.0x400f000000000000 -a lunid SCSI ATTRIBUTES FOR LUN PATH : 0/2/1/0.0x500805f300083899.0x400f000000000000name = lunidcurrent =0x400f000000000000 (LUN # 15, Flat Space Addressing)default = saved = |
The legacy hardware path format for Fibre
Channel disks encodes the target port identifier and LUN id as virtual
hardware elements. It has the following format:
HBA_path.domain.area.port.controller.target.lun
The domain represents the Fibre Channel
switch, the area is the specific port on the Fibre Channel switch into
which the target is plugged. The domain, area, and port values
are extracted from the target port identifier as shown in the table:
Table 1-6 Title not available (Fibre Channel)
| Domain(8 bits) | Area(8 bits) | Port(8 bits) |
|---|
| 0-255 | 0-255 | 0-255 |
The controller, target, and lun values
are extracted from the LUN id as shown in the table:
Table 1-7 Title not available (Fibre Channel)
| Controller(7 bits) | Target(4 bits) | LUN(3 bits) |
|---|
| 0-63 | 0-15 | 0-7 |
To convert a lunpath hardware path to a legacy hardware path,
use the scsimgr get_info command on the target’s hardware path to display
the port_id, which contains the domain, area,
and port values. Extract the controller,
target, and lun values from the
LUN id.
The following example uses lunpath hardware path 0/2/1/0.0x500805f300083899.0x4011000000000000:
# scsimgr get_info -H 0/2/1/0.0x500805f300083899 STATUS INFORMATION FOR TARGET PATH : 0/2/1/0.0x500805f300083899Generic Status InformationSCSI services internal state = IDLEPort id = 0x10700Protocol = fibre_channelProtocol revision = 4.3Port name = 0x500805f300083899Node name = 0x500805f300083890LUN paths registered (active/inactive) = 12 |
A port_id of 0x10700 yields a domain value
of 1, an area value of 7, and a port value
of 0.
The LUN address of 0x4011000000000000, which represents LUN
id 0x11, yields a controller value of 0, a target value
of 2 and a lun value of 1.
The resultant legacy hardware path is 0/2/1/0.1.7.0.0.2.1.
To confirm this mapping, use the ioscan -m hwpath command, as follows:
# ioscan -m hwpath -H 0/2/1/0.0x500805f300083899.0x4011000000000000Lun H/W Path Lunpath H/W Path Legacy H/W Path=============================================================================64000/0xfa00/0x4 0/2/1/0.0x500805f300083899.0x4011000000000000 0/2/1/0.1.7.0.0.2.1 |
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