E20425-01 •
Chapter 3 Operations
39
Sequence Management
Sequence Open
The tape drive considers a Sequence open from the time that the first frame of
the Sequence (the frame with the SOFi3 delimiter) is sent until one of the
following occurs:
•
An end-of-frame (EOF) delimiter is sent with the last sequence bit set
•
A LOGO is sent to, or received from, the Sequence responder
•
The sequence is aborted with ABTS
The tape drive as a Sequence responder considers a Sequence open from the
time that the first frame of the Sequence (the frame with the SOFi3 delimiter)
is received until one of the following occurs:
•
An end-of-frame (EOF) delimiter is sent with the last sequence bit set
•
The Sequence is aborted using ABTS
•
A LOGO is sent to, or received from, the Sequence originator
Sequence Identifier Usage
The sequence identifier (SEQ_ID) is a field in the frame header that sets one
frame apart from another indicating the order in which they occur. The
following paragraphs summarize the rules governing the reuse of SEQ_IDs.
For sequences which transfer Sequence Initiative:
•
A Port can reuse a SEQ_ID for the same Exchange following the
confirmation of Sequence delivery.
•
A Port can reuse the SEQ_ID with a different Exchange (to the same, or a
different destination Port) immediately following transmission of the last
frame of the Sequence without waiting for confirmation of Sequence
delivery.
For sequences which do not transfer Sequence Initiative:
•
Consecutive FCP_DATA Sequences for the same exchange follow the
FC-PH rules for streamed Sequences which include:
a. The first FCP_DATA Sequence after transfer of Sequence Initiative is
not a streamed Sequence. It can use any eligible SEQ_ID and the
SEQ_CNT can be either zero or a continuously increasing number.
b. The second and subsequent Sequences within the same exchange
are treated as streamed.
•
Because frame delivery is not confirmed, the Sequence Initiator cannot
reuse a SEQ_CNT within a given Sequence.
For sequences beginning with a SEQ_CNT of zero, the SEQ_CNT cannot
wrap when reaching a hexadecimal count of “FFFF”.
For sequences beginning with a SEQ_CNT of ‘
n
’ (where
n
is not zero) the
SEQ_CNT can wrap when reaching a hexadecimal count of “FFFF” and
continue from zero up to a value of
n
-1.
Содержание Storage Tek T10000
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Страница 18: ...What s New xx T10000 Interface Reference Manual January 2011 E20425 01...
Страница 30: ...Considerations 12 T10000 Interface Reference Manual January 2011 E20425 01 Figure 5 Cascading Hubs...
Страница 82: ...Private Loop SCSI Target Discovery 64 T10000 Interface Reference Manual January 2011 E20425 01...
Страница 286: ...Glossary 268 T10000 Interface Reference Manual January 2011 E20425 01...
