Seagate Fibre Channel Interface User Manual
Page 143
Fibre Channel Interface Manual, Rev. D
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If the DL value equals the actual transfer length in the CDB, the Residual Over Run and Residual Under Run bits in the
FCP RSP will be cleared.
Logical Unit Number (LUN)
Addresses physical devices or virtual devices attached to a target.
0
Zero is the only valid LUN number for the drives supported by this manual.
The drive will reject Inquiry, Test Unit Ready, and Request Sense commands that select an invalid LUN by sending
Check Condition status in the FCP RSP frame. Inquiry commands will return Inquiry Data with the Peripheral Device
Type field set to Logical Unit Not Present (7Fh). Request Sense and Inquiry commands will send Check Condition
status in response to an invalid LUN selection. For all other commands, the Logical Unit field is not tested.
Read Data
Set to one (1) when the command specified by the CDB field will result in a data transfer to the initiator.
Target Reset
When the drive receives a Target Reset, it clears the command queue for all initiators and returns a Unit Attention status in
response to the next command received from all initiators. N_Port and Process Logins are preserved.
Task Attribute
Specifies the type of command queue management requested for the SCSI command in the CDB field of this FCP CMND.
The drive supports:
0
Simple Queue. Specifies that the I/O process be placed in the drive’s I/O process queue for execution. The order of
execution can be arranged by the disc drive in accordance with a performance optimization algorithm.
1
Head of Queue. Specifies that the I/O process be placed first in that logical unit’s queue for the initiator originating
the I/O process. An I/O process already being executed by the drive is not preempted. A subsequent I/O process
received with a Head of Queue attribute is placed at the head of the queue for execution in last-in, first-out order.
2
Ordered Queue. Specifies that the I/O process be placed in the disc drive’s I/O process queue for execution in the
order received, with respect to other commands with Ordered Queue attributes, except for I/O processes received
with a Head of Queue, which are placed at the head of the queue.
4
ACA Queue. When an ACA condition is active in the drive, only FCP CMNDs with the ACA Queue attribute received
from the initiator that originated the I/O process that caused the ACA condition will be executed.
5
Untagged Queue. Allows the drive to accept only one command from each initiator. If another command is received
for an initiator with an active command, the drive will return a check in the FCP RSP.
Term Task (Terminate Task)
Not supported by the drive.
Write Data
Set to one (1) when the command specified by the CDB field will result in a data transfer from the initiator.