5 task management messages, 1 task management message codes, 2 abort task – Seagate Ultra 320 User Manual
Page 119: Phase. see section 4.5
Parallel SCSI Interface Product Manual, Rev. A
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4.5
Task 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.
4.5.1
Task management message codes
Table 45:
Task management message codes
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.
4.5.2
ABORT 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.
Code
Support
Message name
Direction
Clear attention
condition
IU Transfers Disabled
IU Transfers Enabled
Initiator
Target
Initiator
Target
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