Spectra Logic Spectra S50 User Manual page 89

Table A-8: World Wide Name Target Descriptor Format
Bit
Byte 7
16 (MSB)
17
18
19
20
21
22
23
24
M
The Address Type is 2, and Bytes 5-7 of the target descriptor are defined as the
N_PORT D_ID for the target device.
The D_ID field is the 24-bit (3-byte) Destination Identifier field that is used to actually
route the commands through a fabric. It is dynamic in that the fabric switch can
theoretically change these when a new device is added to the fabric, or any time that
the system is powered on. Typically, however, it will be a fairly consistent value for a
given configuration of cables and switches.
A SHOW LOOP command will return a 6-hex-digit number associated with each loop ID
and WWN; that is the D_ID of each target on the list.
• For direct fabric-attach devices, the LSByte will be 0.
• For arbitrated loop devices, the LSByte will be the Arbitrated Loop Physical Address
(AL_PA) of the device on the loop, which has a fixed relationship to the loop ID.
• The MS-2 bytes of the D_ID are assigned by the fabric, and they are typically
related to the fabric port to which you are plugged in.
The Device Type Field is as identified in Target Descriptors on page 85.
Bytes 8-15 of the target descriptor are defined as the World Wide Name for the target
device.
The Logical Unit Number field specifies the FCP LUN for the target device.
The Device-Type Specific field is defined in Target Descriptor Device-Specific Fields on
page 90.
Appendix A. Extended Copy—83h—143r1 Specifications
6 5 4
Logical Unit Number
Device-Type Specific
89
3 2 1 0
(LSB)