A log device based data storage subsystem provides for the efficient storage and retrieval of data with respect to an operating system executing on a computer system coupled to the data storage system. The data storage system includes a storage device providing for the storage of predetermined file and system data, as provided by the computer system, within a main filesystem layout established in the storage device. The data storage system also includes a log device coupled in the logical data transfer path between storage device and the computer system. The log device provides for the storage of the predetermined file and system data within a log structured filesystem layout established in the log device. A control program, included as part of the data storage system, is executed in connection with the log device and provides log structured filesystem management over the log device to store the predetermined file and system data in one of a plurality of data segments, delimited by a first free data segment and an oldest filled data segment, to selectively clean the oldest filled data segment to the first free data segment, and to selectively transfer the predetermined file and system data from the log device to the storage device. The control program utilizes location data provided in the predetermined file and system data to identify a destination storage location for the predetermined file and system data within the main filesystem layout.