D Addressing, Structures, And Operations - HP N1200 - StorageWorks Network Storage Router User's And Service Manual

D Addressing, structures, and operations
Fibre Channel and SCSI systems employ different methods of addressing devices. The inclusion of a
network storage router requires that a method of translating device IDs be implemented so that each SCSI
device is mapped to the appropriate Fibre Channel LUN. The SCSI buses establish bus connections
between devices. Targets on a SCSI bus may internally address logical units. The addressing of a specific
SCSI device is represented by the BUS:TARGET:LUN triplet.
When a Fibre Channel initiator initializes on a loop, the host must first determine what devices exist on
the loop. Device discovery is performed, and an FCP target device list is built. Each device is queried for
FCP logical units. The logical units are the actual devices that the operating system will address. When an
initiator addresses a logical unit, the LUN field used is consistent in form with the SCC defined fields. All
current Fibre Channel host bus adapter drivers are consistent with these methods. The addressing used is
the SCC Logical Unit Addressing and Peripheral Device Addressing methods, shown in
Table 17. First level addressing is supported, so only the first 2 bytes of the 8-byte FCP LUN are used.
Table 16 SCC addressing structure
7
Bit
Byte
N Address Method
N+1
Table 17 Address method definitions
Codes Description
00 Peripheral Device Addressing Method
01 Volume Set Addressing Method
10 Logical Unit Addressing Method
11 Reserved
Table 18 SCC logical unit addressing
7
Bit
Byte
N 1
N+1
Table 19 Peripheral device addressing
7
Bit
Byte
N 0
N+1
6 5 4
Address Method Specific
6 5 4
0
Bus
6 5 4
0
Target/LUN
N1200-320 4Gb Network Storage Router user and service guide 113
3 2 1
Address Method Specific
3 2 1
Target
LUN
3 2 1
Bus
Table 16
0
0
0
and