1.5 Unit Attention Condition; Generation Of The Unit Attention Condition - Fujitsu MAX3073NC - SCSI,80, Dell DC961,Hard Drive Scsi Logical Interface Specifications

The INIT can specify the following error recovery options by the QErr bit of the control mode parameter
(Page A) of the mode select parameters.
When "00" is specified in the QErr bit, the IDD enters any one of a number of sense hold states, and
when this state is released, it continues to execute the commands in the queue. The IDD queues any
commands received from other INITs while it is in the sense hold state, but during this period, execution
of all the commands in the queue is interrupted.
If "01" is specified in the QErr bit, if the IDD enters any one of a number of sense hold states, the queue
is cleared after the sense hold state is released. When the queue is cleared through this recovery option,
the UNIT ATTENTION condition is generated for all the INITs which had their commands cleared
(excluding the INIT that set the sense hold state). The additional sense code Commands cleared by
another INIT [=2F-00] is set.
If "10" is specified in the QErr bit, the IDD enters any one of a number of sense hold states. When this
sense hold state is released, the queue is cleared of commands from the INIT that entered the sense hold
state.
Deferred errors are reported for all commands that have already been completed. Therefore, the queue
tag values attached to those commands are not reported.
If a QUEUE TAG message is received by the IDD when tagged commands are prohibited by the DQue
bit of the control mode page, the IDD rejects the message with the MESSAGE REJECT message
processes the accompanying command as an untagged command.
The ABORT TASK SET, ABORT TASK, TARGET RESET or CLEAR TASK SET message is used to
clear some or all of the commands in the queue. See "SCSI Physical Interface Specifications" for details.
If '0000', '0001' is specified in the Queue algorithm modifier of the control mode page, the IDD
performs command reordering processing of commands issued with a SIMPLE message. Reordering
processing is performed with the objective of reducing total processing time for command processing.
• Conditions for Reordering:
If a command which is the object of reordering is issued by an INIT that permits reordering with an
accompanying SIMPLE message.
• Commands which are Objects of Reordering:
READ, READ EXTENDED, WRITE, WRITE EXTENDED
If an INIT permits command reordering processing, the IDD changes the processing order of the
commands. It is necessary for the INIT to manage concerning the legality of the data, etc.
Section 4.1.7, "Control mode parameters (page code = 0A)" for details of the control mode page.
1.5 UNIT ATTENTION Condition
The UNIT ATTENTION condition is a function used to notify the INIT asynchronously of an event
(status change) that has occurred in the TARG or logical unit.
1.5.1

Generation of the UNIT ATTENTION condition

Events which cause a UNIT ATTENTION condition to be generated are one of the following.
C141-C010

1.5 UNIT ATTENTION Condition

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