Errors Detected By The Initiator; Buffer Parity Error Handling - Tandberg Data SLR7-140 PROGRAMMER Manual

Tandberg Data
7.6.2.

Errors Detected by the Initiator

The Initiator signals bus parity errors by asserting
ATN. The Drive must acknowledge the ATN by going to the
MESSAGE OUT Phase. The MESSAGE OUT transferred will be
either an INITIATOR DETECTED ERROR message or a MESSAGE
PARITY ERROR message.
When receiving an INITIATOR DETECTED ERROR message or a
MESSAGE PARITY ERROR message the drive may retry the
last phase (the one immediately before the MESSAGE OUT
phase). If the Initiator keeps on asserting ATN and
responding with one of the two above mentioned messages,
the drive will repeat the retry operation until the Bus
Parity Error Retry count has been exhausted. The Bus
Parity Error Retry count is configurable (see the Bus
Parity Error Retry field in the Miscellaneous Parameters
mode page). It can be set to zero. In this case there
will be no retries and the command will be terminated
immediately.
If the previous phase was a DATA IN phase and the last
transferred message was INITIATOR DETECTED ERROR, then
the Drive will go to the MESSAGE IN phase and transfer a
RESTORE POINTERS message. The Drive will then go back to
the DATA IN phase and the data transferred since the
last reconnect (or COMMAND phase) will be transferred
once more to the Initiator. If the Bus Parity Error
Retry count gets exhausted (or if the Bus Parity Error
Retry has been
terminate the command with CHECK CONDITION status. The
Error Code will be I
If the previous phase was a STATUS phase and the last
transferred message was INITIATOR DETECTED ERROR, then
the Drive will go to the MESSAGE IN phase and transfer a
SAVE DATA POINTER message and then a RESTORE POINTERS
message. The Drive will then go back to the STATUS phase
and the Status byte will be transferred once more to the
Initiator. If the Bus Parity Error Retry count gets
exhausted (or if the Bus Parity Error Retry has been
configured to 0), the drive will go to the BUS FREE
phase (creating an Unexpected Bus Free condition).
If the previous phase was a MESSAGE IN phase and the
last transferred message was MESSAGE PARITY ERROR, then
the Drive will go back to the MESSAGE IN phase and the
previous Message byte will be transferred once more. If
the Bus Parity Error Retry count gets exhausted (or if
the Bus Parity Error Retry has been configured to 0),
the drive will go to the BUS FREE phase (creating an
Unexpected Bus Free condition).
7.7.

Buffer Parity Error Handling

The Drive will
transferring data from the data buffer to the tape. When
a buffer parity error has been detected the drive will
re-write the data until the parity error goes away or
until the Write Retries count has been exhausted.
7-11 Tandberg SLR Product Line SCSI Functional Specifications
configured to
NITIATOR DETECTED ERROR MESSAGE RECEIVED
check for buffer
General Exception Handling
0), the drive
parity errors
will
.
when