Overview: The Next Generation Mass Storage Stack (September 2009)
Table Of Contents
- Abstract
- Background
- Features of the Next Generation Mass Storage Stack
- Impact
- Background
- Impact
- Background
- Impact
- Background
- Impact
- Impact
- Introduction to the Agile View
- Changes to I/O and Mass Storage Subsystems
- Changes to Other Subsystems
- Migrating to the Agile View
- Conclusion
- Glossary
- Appendix A: Summary of Changes
- Appendix B: Using ioscan
- Appendix C: Using scsimgr
- Appendix D: Interpreting Lunpath Hardware Paths
- For more information
57
Appendix D: Interpreting Lunpath Hardware Paths
This appendix 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.
Components of Lunpath Hardware Paths
The lunpath hardware path has three parts: the HBA path, the target address, and the LUN address.
• The HBA path is composed of a series of bus-nexus addresses separated by a slash (/). It is identical to
the HBA portion of a legacy hardware path.
• The target address is transport-specific. If the SCSI transport supports port naming, the target address is
a port name. Otherwise, the target address is a port identifier. When printed by I/O commands like
ioscan, the target address is separated from the HBA path by a period (.) and is printed in hexadecimal
notation.
• The LUN address is a SCSI 64-bit LUN identifier, built from the address method and the LUN number.
When printed by I/O commands, it is separated from the target address by a period (.) and is printed in
hexadecimal notation.
The following table shows four examples:
Lunpath Hardware path HBA
path
Target address LUN address
0/1/1/0.0x1.0x0 0/1/1/0
0x1 0x0
2/0/1.0x5.0x0 2/0/1
0x5 0x0
0/5/1/0.0x50060e8004276e12.0x4000000000000000 0/5/1/0
0x50060e8004276e12 0x4000000000000000
0/4/1/0.0x500805f300083899.0x4010000000000000 0/4/1/0
0x500805f300083899 0x4010000000000000
Parallel SCSI
Because parallel SCSI does not support port naming, the target address for a parallel SCSI device is the target
port identifier, a value between 0x0 and 0xf.
The LUN address is the LUN number, a value between 0x0 and 0x7.
The legacy hardware path
can be easily derived from the lunpath hardware path. The only difference is that
the target and LUN addresses in the legacy hardware path are displayed in decimal instead of hexadecimal.
The following table shows four example lunpath hardware paths and their equivalent legacy hardware paths for
parallel SCSI devices:
Lunpath Hardware Path Legacy Hardware Path
0/0/2/0.0x0.0x0 0/0/2/0.0.0
0/1/1/0.0x1.0x0 0/1/1/0.1.0
0/1/1/0.0x7.0x0 0/1/1/0.7.0
0/0/2/1.0xf.0x0 0/0/2/1.15.0
Fibre Channel
The target address for a Fibre Channel device is the target port 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: