Fibre Channel Data Constructs Fibre Channel Data Constructs
ULP Information Transfer
SCSI-FCP Write Operation
Initiator
1 FCP_CMD IU 1 Sequence 2 Exchange 5 FCP_DATA IU 3 Sequence 4
6
Sequence 3 Frame
8
FCP_RSP 7 IU 4
2
Fabric
Frame
Frame Frames
4
Sequence 1
Target
FCP_XFR_ RDY
IU 2
3
This diagram illustrates a SCSI-FCP write operation:
1. The initiator node generates a SCSI write request (FCP_CMD), which is packaged by the FC-4 layer as IU 1.
2. The initiator FC-2 layer converts IU 1 to a single command chunk and sends it across the fabric as a single frame. This constitutes Sequence 1.
3. The target node responds with a SCSI write request response (FCP_XFR_RDY), which is packaged as IU 2. The write request response is required for synchronization between the initiator and target.
4. The target FC-2 layer converts IU 2 to a single command chunk and sends it across the fabric. This constitutes Sequence 2.