Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
33
_____________________________________________________________________________________
•
Ordered Queue Tag (22h)
The ORDERED QUEUE TAG message specifies that the I/O process be placed in the disc drive’s I/O
process queue for execution in the order received, with respect to other commands with ORDERED
QUEUE TAG messages, except for I/O processes received with a HEAD OF QUEUE TAG message,
which are placed at the head of the queue.
•
Simple Queue Tag (20h)
The SIMPLE QUEUE TAG message specifies that the I/O process be placed in the disc drive’s I/O
process queue for execution. The order of execution can be arranged by the disc drive in accordance
with a performance optimization algorithm. The SIMPLE QUEUE TAG message is also sent by the target
when reconnecting to the initiator.
Restore Pointers (03h)
The RESTORE POINTERS message is sent from a target to direct the initiator to restore the most recently
saved pointers (for the current nexus) to the active state. Pointers to the command, data, and status locations
for the nexus shall be restored to the active pointers. Command and status pointers shall be restored to the
beginning of the present command and status areas. The data pointer shall be restored to the value at the
beginning of the data area in the absence of a SAVE DATA POINTER message or to the value at the point
where the last SAVE DATA POINTER message occurred for that nexus.
Save Data Pointer (02h)
The SAVE DATA POINTER message is sent from a target to direct the initiator to save a copy of the present
active data pointer for the current nexus. (See 3.4 for a definition of pointers.)
Synchronous Data Transfer (01h)
See Paragraph 3.5.3.2 on EXTENDED MESSAGE.
Terminate I/O Process (11h)
This message is supported only on those drives having it as a factory installed option.
The Terminate I/O Process message is sent from the initiator to the target to terminate the current I/O pro-
cess without corrupting the medium.
With the following exceptions, the target shall terminate the current I/O process and return COMMAND
TERMINATED status. The sense key shall be set to NO SENSE. The additional sense code and qualifier are
set to I/O PROCESS TERMINATED.
