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Note
In disconnect processing in this case, transfer of all the data accompanying execution of the command
is completely and there is actually no necessity for the SAVE DATA POINTER message.
However, by issuing the SAVE DATA POINTER message, processing time increases due
to the message transfer, but as a result of the pointer restore operation that is executed
internally by the INIT during reconnection processing for the status report, the current data
pointer can reflect the final results of the data transfer.
(5)
Disconnect Processing Exceptions
When the previously mentioned disconnect processing is executed, if the ATTENTION condition is
generated for the DISCONNECT message sent by the IDD and the INIT returns the MESSAGE
REJECT message, the IDD executes the command with the connections to the SCSI bus remaining
as is, without executing disconnect processing. Cases of disconnect processing in which a pointer
operation is necessary and the SAVE DATA POINTER message is rejected are the same.
(6)
Reconnection Processing Procedure
The reconnection processing procedure is as shown below.
1) The IDD executes the ARBITRATION phase at the point when processing on the SCSI
bus is necessary and acquires the right to control the SCSI bus, then reconnects with the
INIT in the RESELECTION phase.
2) After that, the IDD sends the IDENTIFY message to the INIT and notifies it of the logical
unit number (LUN) necessary for reconnection processing. If a tagged queuing command
is executed, the TARG sends the SIMPLE QUEUE TAG message to inform the INIT of
the tag ID.
corresponding to the LUN specified at this time and restores it to the current pointer.
Note:
1) If there is no response to the INIT within the specified time (default: 250 ms) in the
RESELECTION phase, the IDD performs time out processing, then enters the BUS FREE
phase. In this case, after waiting 200
number of retries (re-executing the RESELECTION phase). However, if it still cannot
reconnect with the INIT after that, the IDD clears the command necessary for reconnection
processing and generates sense data indicating ABORTED COMMAND[=B]/Select
/Reselect failure[=45-80].
2) If the NIT rejects the IDENTIFY message, or if the SIMPLE QUEUE TAG message is rejected
when executing a tagged queuing command, the IDD clears the command that was being
executed during reconnection processing and enters the BUS FREE phase. In this case, the IDD
generates sense data indicating ABORTED COMMAND[=B]/Message error[=43-00].
3) After the INIT that accepts the IDENTIFY message normally completes the pointer restore
operation, it should make the ACK signal for the IDENTIFY message FALSE. If the
ATTENTION condition does not exist when the ACK signal becomes FALSE during
sending of the IDENTIFY message, the IDD regards the reconnection processing as having
been normally completed and begins subsequent processing.
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The INIT fetches the save (Saved) pointer (command, data and status)
C141-E039-01EN
s or longer, the IDD executes the predetermined
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