[T11.3] FCP-4: Sequence Count to zero on retries

David Peterson dpeterso at brocade.com
Mon May 7 09:45:07 PDT 2007


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Below is a resend of an email asking for feedback on the requirement to
set the Sequence Count to zero for a retransmitted FCP_DATA IU. 
There has been no feedback to the previous message and this will be my
final reflector message regarding this issue. 
Please respond asap if you have an interest in SRR behavior.
Thanks...Dave 
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Dave also directed the group to an inconsistency in FCP on the
maintenance of the Sequence Count in the event of Sequence retry with
CISC. He asked the community whether the Sequence Count "may" or "shall"
restart at zero for the retry. See FCP-4 subclauses 8.2, 12.4.1.6, and
12.4.1.7 for the inconsistent statements. 
ACTION: Dave Peterson to contact tape vendors to see whether they are
able to force the Sequence Count to zero on Sequence retries. 
>From FCP-4 Rev 00a: 
8.2 Sequence Retransmission Request (SRR) 
For unacknowledged classes, the Sequence Count for a retransmitted
FCP_DATA IU shall start at zero, even if continuously increasing
sequence count is being used. 
12.4.1.6 FCP_DATA IU recovery - write operations 
For unacknowledged classes, the SEQ_CNT field value may start at zero,
even if continuously increasing sequence count is being used. 
12.4.1.7 FCP_DATA IU recovery - read operations 
For unacknowledged classes, the SEQ_CNT field value may start at zero,
even if continuously increasing sequence count is being used. 
David Peterson
Brocade, Office of the CTO
INCITS T11 International Representative
david.peterson at brocade.com
cell: 612-802-3299
(no disclaimer)



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