Open SCSI Integrator's Manual for NonStop S-Series Servers

The SCSI SAC
Open SCSI Integrator’s Manual for NonStop Servers—422988-002
7-9
Initiator Detected Error(05h)
phase. The target must reconnect using a reselection sequence to continue the current
SCSI operation.
This message is valid only if the privilege to disconnect has been granted by the SCSI
SAC. Otherwise, the SCSI SAC responds with a Message Reject message to prevent the
target from disconnecting. If the target proceeds with the unauthorized disconnection,
the SCSI SAC treats this as an unexpected disconnect. Subsequent reconnection by the
target is treated as an illegal reconnection (see Reconnection
on page 7-11).
Initiator Detected Error(05h)
The SCSI SAC issues the Initiator Detected Error message in the message-out phase to
inform the target that the SCSI SAC has received a status with bad parity. This message
allows the target to retry the status phase in order to resend the status.
The SCSI SAC expects the target to initiate a retry by using the sequences described
under Target-Initiated Retry
on page 7-11. If the target does not initiate a retry or if the
retransmitted status also fails with bad parity, the SCSI SAC initiates the termination
sequence and reports an error to the host.
Abort (06h)
The Abort message is issued by the SCSI SAC in the message-out phase to clear the I/O
process. In addition to its SCSI-2-defined functions, this message is also used to
terminate invalid phase transitions and invalid reconnection requests from the target.
The SCSI SAC expects the target to make a transition to the bus-free phase.
Previously established conditions, including data-transfer agreement and mode-select
parameters, are not affected by the Abort message.
Message Reject (07h)
Either the SCSI SAC or target issues the Message Reject message to indicate that a
received message is inappropriate or has not been implemented.
Except for the SDTR message, the SCSI SAC does not expect a Message Reject
message from the target. An unexpected Message Reject message from the target causes
the SCSI SAC to initiate the termination sequence and report the error to the host.
No Operation (08h)
In response to a target’s request for a message, the SCSI SAC issues a No Operation
message when it does not have any message to send.
The SCSI SAC issues this message when the target unexpectedly enters the message-out
phase. The SCSI SAC does not consider this an error condition. However, if the target
reenters the message-out phase immediately following the acceptance of this message,
the SCSI SAC issues an Abort message and reports the error to the host.