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1.6.4 Exceptional event processing of a drive
If an exceptional event of the SAS protocol system (refer to Table 1.45) occurs in
a drive, the drive temporarily rejects an SSP frame from the SSP INIT port due to
recovery processing (abort processing). Therefore, the drive may return the
OPEN_REJECT (RETRY) primitive for the connection request from an initiator.
This is because the drive cannot perform abort processing completely while
receiving an SSP frame from the SSP INIT port.
The processing sequence a drive performs for an exceptional event (Table 1.45) is
as follows:
1) After an exceptional event occurs, the CREDIT_BLOCKED primitive instead
of an RRDY primitive is sent to stop SSP frames from the initiator.
2) The connection is temporarily closed.
3) The recovery processing for the exceptional event (abort processing) is
started.
4) If the recovery processing has not been completed, the OPEN_REJECT
(RETRY) primitive is sent in response to the connection request from the
initiator.
5) After the recovery processing for the exceptional event, an OPEN frame is
sent so that the result of the recovery processing can be reported later with a
RESPONSE frame.
6) When the OPEN_ACCEPT primitive is received from the initiator, the drive
sends the CREDIT_BLOCKED primitive instead of an RRDY primitive.
7) A RESPONSE frame is sent.
8) The connection is closed. This completes the recovery processing for the
exceptional event.
C141-C009
1.6 Transport layer
1-79
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