Task Attribute Messages - Fujitsu MAN3184 SERIES Specifications

When the TARG is ready to transfer data for a disconnected task for which a TARGET
TRANSFER DISABLE message has been sent, the TARG shall reconnect to the INIT for the task
(via a reselection phase and consecutive message in phases containing an IDENTIFY message, and
an optional SIMPLE message), send a DISCONNECT message, and, if the INIT does not respond
with a MESSAGE REJECT message, generate a bus free phase. This connection serves to notify
the INIT that the task is ready for data transfer. If the INIT rejects the DISCONNECT message,
the TARG may generate a data in or data out phase; otherwise, the INIT may reconnect to the task
as described in the CONTINUE TASK message to perform the data transfer.
INITs should avoid sending the TARGET TRANSFER DISABLE message to the TARG that have
not implemented this message. Such the TARG may not respond as described in this section. An
application client can determine whether a device server implements this message by examining
the (TRANDIS) bit in the standard INQUIRY data.
The application client shall inform the INIT to use the CONTINE TASK message by issuing a
TARGET TRANSFER DISABLE link control function in the send SCSI command phase.
2.3.16

Task attribute messages

Bit
7
Byte
0
1
The task attribute messages define a queue tag of I/O operation. The TAG field is an unsigned
eight-bit integer to be assigned by the INIT when it issues a command.
When the INIT issues a command using a tagged queuing, the INIT sends the appropriate task
attribute messages immediately after the IDENTIFY message during the same MESSAGE OUT
phase in order to set the queue tag for the I/O operation. If the task attribute messages are not sent,
the I/O operation is treated as an untagged command.
If the TARG reconnects to the INIT to continue a tagged I/O operation, the TARG sends the
SIMPLE message immediately after the IDENTIFY message in the reconnection sequence of the
same MESSAGE IN phase.
(1) SIMPLE message: X'20'(I
The SIMPLE message specifies that the task be placed in that logical unit's queue. The order of
execution is determined by the IDD.
6 5 4
Message Code (X'20', X'21', or X'22')
TAG (X'00'- X'FF')
T)
C141-E123-01EN
3 2 1 0
2 - 13