Methods and systems for drilling subsea wells bores with dual-gradient mud systems include drilling the subsea well bore while employing a subsea pumping system, a subsea choke manifold and one or more mud return risers to implement the dual gradient mud system. The optical transport system includes a light transmission line for transmitting light bi-directionally and a plurality of nodes, connected in series by the light transmission line for receiving, extracting and passing signal light. The virtual partition is stored as a file within the file system of the storage device.