Quantum DLT 4000 Product Manual page 169

DLT4000 SCSI Interface
ABORT (06h)
This message is sent from the initiator to the target to clear, on the selected unit, the
current I/O process. Buffered (cached) write operations will be completed if possible.
The target goes directly to the BUS FREE phase after successful receipt of this
message. Current settings of Mode Select parameters and reservations are not affected.
Commands, data, and status for other initiators is not affected.
This message can be sent to a logical unit that is not currently performing an
operation for the initiator. If no unit has been selected, the target goes to BUS FREE
and no commands, data, or status on the target is affected.
ABORT TAG (0Dh)
This message is sent from the initiator to the target to clear, on the selected unit, the
current I/O operation only. The target goes directly to the BUS FREE phase after
successful receipt of this message. Current settings of Mode Select parameters and
reservations are not affected. The data on the cache will be flushed to the tape.
BUS DEVICE RESET (0Ch)
This message from an initiator clears all commands, data, and status in the tape
controller. When it recognizes this message, the drive flushes the cache to tape and
proceeds to the BUS FREE state. The drive then executes a hard reset which leaves it
as if a Bus Reset had occurred.
CLEAR QUEUE (0Eh)
This message clears all I/O processes for all initiators. A Unit Attention condition will
be generated for all other initiators that had outstanding I/O processes, with
Additional Sense Code (ASC) of Command Cleared by Another Initiator. The target
goes directly to the BUS FREE phase after successful receipt of this message. Current
settings of Mode Select parameters and reservations are not affected. The data on the
cache will be flushed to the tape.
COMMAND COMPLETE (00h)
This message is sent from a target to an initiator to indicate that the execution of a
command (or a series of linked commands) has completed and valid status has been
sent to the initiator. After it has sent the message successfully, the target goes to the
BUS FREE phase by releasing BSY. If received by the tape unit, it is handled as an
illegal message; the drive returns MESSAGE REJECT and enters the STATUS phase
reporting CHECK CONDITION with the sense key set to COMMAND ABORTED.
DISCONNECT (04h)
A target sends DISCONNECT to tell an initiator that the present physical path is
going to be broken (the target intends to disconnect by releasing BSY). Later,
reselection is required in order to complete the current operation. This message does
not cause the initiator to save the Data pointer.
DLT4000/DLT4500/DLT4700 Cartridge Tape Subsystem 8-9