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SCSI Interface Product Manual, Rev. J
[3]
In a multi-initiator or queued environment, an initiator's attempt to prevent disconnection (by clearing the
DiscPriv bit in the initial Identify message or in a subsequent Identify message, or by rejecting a Discon-
nect message) may result in the target terminating the associated command with a status of Busy.
[4]
Responses by number follow:
1
Continue (see Note [3] for multi-initiator or queued environment considerations). The Continue
response indicates that the target will continue execution of the current task. If the message sent
to the target is a wide or a synchronous negotiation request, the target will complete the negotia-
tion prior to continuing the task.
2
Enter Bus Free state. No sense data will be set up.
3
Send Message Reject message.
4
Unexpected Bus Free without sense data set up. The Unexpected Bus Free response includes
going directly to bus free (ATN signal is ignored if present) and terminating the current task. Since
no sense data will be set up, a Contingent Allegiance condition will not be established.
5
Retry Message phase. On a Message Out phase, the target will continue to receive message
bytes from the initiator until the ATN signal is deserted. The target will then remain in the Message
Out phase and assert REQ, to notify the initiator that the entire Message Out phase needs to be
repeated. Following failure of a product-specific number of retries, the target will switch to
response C.
On a Message In phase, the target will resend the last message. Following failure of a product-
specific number of retries, the target will switch to response C.
6
Send Restore Pointers message, and retry phase.
7
Go to Status phase and report Check Condition status (see Note [3] for multi-initiator or queued
environment considerations). Associated sense data will have a sense key of Aborted Task (0Bh).
The sense code will either indicate an Initiator Detected Error message was received or that a Par-
ity Error was detected, as applicable.
8
Continue with no disconnect (see Note [3] for multi-initiator or queued environment consider-
ations). This is a special case of response 1. The target should continue the I/O process without
releasing the bus. The target may attempt to disconnect at a later time.
9
Resend message (Disconnect or Task Complete). If the message sent to the target is a wide or a
synchronous negotiation request, the target will complete the negotiation prior to resending the
command complete or the disconnect message.
A
If Message In is Save Data Pointer, do response 8. Otherwise, do response 1.
B
Do not respond to the selection.
C
Unexpected Bus Free with sense data set up. The Unexpected Bus Free response includes going
directly to Bus Free (ATN signal is ignored if present) and terminating the current command. The
sense data will be set up for the failing initiator with a sense key of Aborted Task (0Bh) and a
sense code of Invalid Message Error (49h). A Contingent Allegiance condition will be established.
Exception: If the Unexpected Bus Free occurs due to a message retry failure (response 5), the
sense code will be set to either indicate an Initiator Detected Error message was received or that
a Parity Error was detected, as applicable.
N/A
Not applicable.
41
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