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Quantum DLT 7000 Tape System 4-5
4.2 SUPPORTED SCSI MESSAGES
Following are descriptions of each of the messages supported by the drive.
4.2.1 ABORT Message (06h)
This message is sent from the initiator to the target to clear the current I/O
process on the selected unit. Buffered (cached) write operations are 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
are 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 phase and no commands, data, or status on the target are affected.
4.2.2 BUS DEVICE RESET Message (0Ch)
The BUS DEVICE RESET message is sent from an initiator to direct the drive to
clear all I/O processes on the drive. The message causes the drive to:
1. Flush the contents of cache to tape and go to the BUS FREE phase.
2. Execute a hard reset, leaving it as if a Bus Reset had occurred.
The drive creates a Unit Attention condition for all initiators after accepting and
processing a Bus Device Reset message. The additional sense code is set to
POWER ON, RESET, or BUS DEVICE RESET OCCURRED.
4.2.3 COMMAND COMPLETE Message (00h)
The COMMAND COMPLETE message is sent by the drive to an initiator to
indicate that an I/O process has completed and that valid status has been sent
to the initiator. After successfully sending this message, the drive goes to the
BUS FREE phase by releasing the BSY signal. The drive considers the message
transmission successful when it detects the negation of ACK for the
COMMAND COMPLETE message with the ATN signal false. If a COMMAND
COMPLETE message is received by the tape drive, it is handled as an illegal
message: the drive returns MESSAGE REJECT and enters its STATUS phase,
reporting CHECK CONDITION with the sense key set to COMMAND
ABORTED.