In a SAN environment, an initiator (on the Windows host) initiates a SCSI I/O operation to a target (storage system). The operation can be initiated using either the FC or the iSCSI protocol, depending on the type of initiator installed on your Windows host and the setup on the target. A target can receive SCSI requests using FC if a supported HBA is installed and FC is licensed. Similarly, a target can receive SCSI requests using iSCSI if a supported HBA or the Microsoft iSCSI Software Initiator is installed, and if iSCSI is licensed.
After a target receives a SCSI I/O request, the appropriate operation is performed by writing data to or fetching data from the LUN.