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
58
# 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:
Addressing Method
(2 bits)
LUN Number
(14 bits)
Reserved
(48 bits)
00 – Peripheral Device Addressing
01 – Volume Set Addressing (Flat Space Addressing)
10 – Logical Unit Addressing
0x00-0x3fff 0x00
Because 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 the addressing 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 lunid attribute. For example:
# scsimgr get_attr -H 0/2/1/0.0x500805f300083899.0x400f000000000000 -a lunid
SCSI ATTRIBUTES FOR LUN PATH : 0/2/1/0.0x500805f300083899.0x400f000000000000
name = lunid
current =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 to which
the target is plugged in. The domain, area, and port values are extracted from the target port identifier as shown
in the table:
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:
Controller
(7 bits)
Target
(4 bits)
LUN
(3 bits)
0-63 0-15 0-7