Sun Oracle Storage Tek T10000, Reference Manual

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E20425-01 • Chapter 3 Operations 49
FCP Information Units
Transfer Ready Information Units
The Transfer Ready Information Unit (I1) is a single-frame sequence.
For write operations:

The FCP_XFER_RDY is sent before each write data sequence.
For read operations:

The FCP_XFER_RDY IU (I2) is not used during read type (data in) operations.
This is indicated by setting the ‘READ XFER_RDY DISABLED’ bit during
process login.
Data Information Unit
The Data Information Units (T6 and I3) are either single- or multiple-frame
sequences.
The FCP_DATA IU transfers data associated with an operation. This data
includes logical data to or from tape, as well as command parameter data
(such as Mode Select data) or command response data (such as Mode Sense
data).
Write Data
For write data sequences (such as mode select and write commands), the
parameter field of the first frame sequence is set to the relative offset specified
by the corresponding FCP_XFER_RDY. Then use continuously increasing
relative offset values for subsequent frames.
Read Data
For read sequences (such as mode sense and read commands), the relative
offset on consecutive frames within a read sequence is continuously
increasing.
During read commands with multiple data (I3) sequences, Ports treat all data
sequences other than the first as streamed sequences and follow the rules
associated with streamed sequences.
Response Information Unit
The Response Information Unit (I4) are single- or multiple-frame sequences.
The first two bits (30 and 31) of the first word of a command status frame
payload fall into the following categories:
• 00 = Successful and complete
• 01 = Successful but incomplete
• 10 = Unsuccessful but complete
• 11 = Unsuccessful and incomplete