Virtual TapeServer SCSI-to-FC Adapter User Manual

C-4
Appendix C: Addressing, Structures, and Operation
Table C-6. Indexed Addressing Table
SCC Addressing Option
When a VT5900-SA device is configured to use SCSI Controller Commands (SCC) addressing,
the unit is capable of responding as a controller device to the FCP Initiator, or routing the FCP
request to a specified BUS:TARGET:LUN. When a request using the Peripheral Device
Addressing Method is received (An FCP command with the LUN field with bits 7 and 6 of byte 0
are set to 0), the unit routes the request to the internal processor, which acts on the command
directly. When a request using the Logical Unit Addressing Method is received (bits 7 and 6 set to
10b), the request is routed to the BUS:TARGET:LUN as specified in the defined field.
Host systems using SCC addressing will typically do initial device discovery using the Peripheral
Device Addressing method. On issuing an INQUIRY command to the VT5900-SA, the host will
receive the VT5900-SA Inquiry data, indicating the device type as a controller device (Inquiry
data indicates device type is 0xC). The host will then know, on this basis, that subsequent
commands to VT5900-SA attached devices will use the Logical Unit Addressing method.
The host can perform discovery by either walking through the BUS:TARGET:LUN values as
would a standard SCSI driver, or by issuing a REPORT LUNS command. This command is sent to
FCP LUN Value SCSI BUS:TARGET:LUN
0 0:0:0
1 0:1:0
2 0:2:0
3 0:3:0
4 0:4:0
5 0:5:0
6 0:6:0
(0:7:0 occupied by Initiator ID)
7 0:8:0
(...) (...)
13 0:14:0
14 0:15:0
15 1:0:0
16 1:1:0
17 1:2:0
(...) (...)