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18 Interface Implementation
Bus Parity Errors (Parallel SCSI only)
On detecting a bus parity error during a Command or Data Out phase or
receiving an Initiator detected error message during a Data In or Status phase,
the drive attempts to retry the bus phase. A Restore Pointers message is sent to
the initiator and the transfer is repeated. Only one retry is attempted. If the
retry fails or the restore pointers message is rejected, then the drive goes to
status phase and attempts to report
CHECK CONDITION status. If this fails with
an initiator detected error message, the drive goes to bus free. The sense key is
set to
ABORTED COMMAND with additional sense of 4A00h (command phase
error) or 4B00h (data phase error).
If an Initiator Detected Error or Message Parity Error message is received
during Message In phase, the initiator has detected an error in the message.
The drive will go to Message In and resend the message that was in error. If the
subsequent message is rejected with an Initiator Detected Error, then the drive
goes to Status phase and sends
CHECK CONDITION status. The sense key is set
RESERVE UNIT
The command completes.
REWIND
The command completes.
SEND DIAGNOSTIC
Vendor Unique
SPACE
The logical position is set back to that at the start of the operation unless the
operation has passed its “point of no return”, in which case the operation
completes.
TEST UNIT READY
None
WRITE
The data up to first record boundary in the current burst is written to tape.
Any subsequent data is discarded. If there is no record boundary in the
current burst, the record is truncated to the amount of data transferred and
written to tape.
WRITE BUFFER
If data transfer is complete, command is completed, otherwise, no action is
taken.
WRITE FILEMARKS
The command completes.
VERIFY
The logical position is set to the next record boundary after the point where
the verify was aborted.
Command Abort Processing