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The INIT can specify 2 error recovery options by the QErr bit of the control mode parameter
(Page A) of the mode select parameters.
When "0" is specified in the QErr bit, the IDD enters any one of a number of sense hold states,
and when this state is cleared, 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, but execution of all the commands in the queue is interrupted. In order for
recovery to occur, all the commands used must be untagged commands.
processing, all the commands in the queue, or a portion of them, can be removed from the
queue.
If "1" 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 cleared. When the queue is cleared through
this recovery option, the UNIT ATTENTION condition is held for all the INITs which had
their commands cleared (excluding the INIT that set the sense hold state). The sense code
Commands cleared by another INIT [=2F-00] is set.
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, it rejects the message with the MESSAGE REJECT
message processes the accompanying command as an untagged command.
The ABORT, ABORT TAG, BUS DEVICE RESET or CLEAR QUEUE messages are used to
clear some or all of the commands in the queue. See "OEM Manual Interface Specifications"
for details.
If '0001' is specified in the Queue algorithm modifier of the control mode page, the IDD
performs command reordering processing of commands issued with SIMPLE QUEUE TAG
messages. 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 QUEUE TAG.
• 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.
See 3.1.5, "MODE SELECT" for details of the control mode page.
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In recovery
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