Quantum 10K II - Manual (Page 351)

Appendix B. SCSI Bus Signal Timing
B–30 Quantum Atlas 10K II Ultra 160/m SCSI Hard Disk Drives
Bit 7 6 5 4 3 2 1 0
Identify DiscPriv LUN
Figure B–2 IDENTIFY Message — Data Format
Table B–14 IDENTIFY Message — Field Description
Field Description
Identify The Identify bit must be set to 1. This identifies this message as an
IDENTIFY message.
DiscPriv Disconnect Privilege. This bit must be set to 1 for all tagged tasks (that
is, a QUEUE TAG and QUEUE TAG message follow the IDENTIFY
message). If not set to 1, the drive returns BUSY status.
LUN Only one Logical Unit Number shall be identified per task. The drive
supports a single Logical Unit Number (LUN 0). A non-zero value in this
field causes the drive to terminate the command with a CHECK
CONDITION status, a Sense Key of ILLEGAL REQUEST, and an Additional
Sense of LOGICAL UNIT NOT SUPPORTED.
B.8.8 IGNORE WIDE RESIDUE Message (23h)
The drive sends the IGNORE WIDE RESIDUE Message to indicate that the number
of valid bytes sent during the last REQ/ACK handshake is less than the negotiated
transfer width. The Ignore Field contains the number of invalid data bytes
transferred.
B.8.9 INITIATE RECOVERY Message (0Fh)
The drive informs the initiator that it is entering an Auto Contingent Allegiance
condition (ACA) by sending an INITIATE RECOVERY message immediately
following either a CHECK CONDITION or a COMMAND TERMINATED status.
The ACA remains in effect until it is terminated.
A MESSAGE REJECT response to an INITIATE RECOVERY message indicates that
an ACA shall not be established. The enabled or disabled status of an ACA is not
changed by the rejection of an INITIATE RECOVERY message.
B.8.10 INITIATOR DETECTED ERROR Message (05h)
The INITIATOR DETECTED ERROR message is sent from an initiator to inform the
drive that an error has occurred that does not preclude the drive from retrying the
operation. The source of the error can be related to previous activities on the SCSI
us or can be internal to the initiator and unrelated to any previous SCSI bus
activity. As shown in Table B-15, the drive’s response to and its handling of the
message are based on when, in the task, the initiator introduces the message.