Seagate Ultra 160, Ultra 320 manual Task management messages, Abort Task, 0Eh

4.5Task management messages

Table 45 lists the codes used for messages that manage tasks. Details about these task management mes- sages is given in subsections following the table.

4.5.1Task management message codes Table 45: Task management message codes

			Support
Code
	IU Transfers Disabled			IU Transfers Enabled				Clear attention
	Initiator	Target		Initiator	Target	Message name	Direction	condition
0Dh	Q		Q	M	M	ABORT TASK	Out	Yes
06h	O		M	N/A	N/A	ABORT TASK SET	Out	Yes
16h	O		O	N/A	N/A	CLEAR ACA	Out	Not required
0Eh	Q		Q	N/A	N/A	CLEAR TASK SET	Out	Yes
17h	M		O	N/A	N/A	LOGICAL UNIT RESET	Out	Yes
0Ch	O		M	O	M	TARGET RESET	Out	Yes
Key:
M = Mandatory support			O = Optional support Q = Mandatory if tagged queuing is implemented
In = Target to initiator			Out = Initiator to target

Yes = Initiator shall clear the attention condition before last ACK of the MESSAGE OUT phase.

Not required = Initiator may or may not clear the attention condition before last ACK of the MESSAGE OUT phase (see Section 5.1).

N/A = Not applicable. The receiving SCSI device shall reject this message.

4.5.2ABORT TASK

The ABORT TASK message is defined in the SCSI Architecture Model-4 standard.

In addition to the requirements in the SCSI Architecture Model-4 standard, the target shall go to the Bus Free phase following the successful receipt of the ABORT TASK message.

If only an I_T nexus has been established, the target shall go to the Bus Free phase. No status or message shall be sent for the current task and no pending data, status, or tasks are affected.

Note. The ABORT TASK message in the case of only an I_T nexus is useful to an initiator that is not able to get an Identify message through to the target due to parity errors and just needs to end the current task. Any pending data, status, or tasks for the I_T nexus are not affected. It is not possible to abort an I_T nexus on a physical reconnection because of item (f) in Section 5.1.

On a physical reconnection, the ABORT TASK message aborts the current task if it is fully identified. If the cur- rent task is not fully identified (i.e., an I_T_L nexus exists, but the target is doing a physical reconnecting for an I_T_L_Q nexus), then the current task is not aborted and the target goes to the BUS FREE phase.

Note. A nexus may not be fully identified on a physical reconnection if an attention condition is created dur- ing the Identify message and the target has any tagged tasks for that initiator on that logical unit.

It is not an error to issue this message to an I_T_L or I_T_L_Q nexus that does not have any pending tasks.

Parallel SCSI Interface Product Manual, Rev. A 105