1 HV Installation and Operations Guide

229

Addressing, Structures and

Operation

Fibre Channel and SCSI systems employ different methods of addressing

devices. The inclusion of a bridge 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 are shown in Table <$elemparanumonly and Table

<$elemparanumonly. First level addressing is supported, so only the first 2

bytes of the 8 byte FCP LUN are used.

Table 22 SCC Addressing Structure

Bit

Byte

7 6 5 4 3 2 1 0

Address

Methods

Address Method Specific

N+1

Address Method Specific