HP Surestore 28/48-Slot with DLT7000 Digital Linear Tape SCSI-2 Drive and SCSI - Page 35

SCSI Command Overview Library Control Commands When received from an initiator, the tape drive may respond in one of two ways: • It may take the message as a request by the initiator to disconnect and comply by entering the Message In phase and sending the DISCONNECT message back to the initiator (possibly preceded by the SAVE DATA POINTERS message). In this case, it will delay a minimum of 200 microseconds before arbitrating for the bus again. • Alternately, it may enter the Message In phase and return MESSAGE REJECT. Initiator-Detected Error 05H, The initiator sends this message to inform a target that an error (for example, a bus parity error) has occurred, which does not prevent the target from retrying the operation. When received, the tape drive attempts to retransfer the last command, data, or status bytes by using the RESTORE POINTERS message. Abort 06H, The initiator sends this message to the target to clear, on the selected unit, the current I/O process. The following then occurs: • Buffered (cache) write operations will be completed if possible. • The target goes directly to the BUS FREE phase after receiving this message. • Current settings of Mode Select parameters, reservations, commands, data, and status for other initiators are not affected. This message can be sent to a logical unit that is not currently performing another operation for the initiator. If it does not select a unit, the target goes to BUS FREE, which does not affect any commands, data or status on the target. Chapter 1 1- 11