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.