A method of operating a file system in a host configured to store write data in a data storage device including a first region and a second region is disclosed, and includes; receiving a write data request for write data associated with a file, classifying the write data as hot data or cold data using file meta data for the file, and if the write data is classified as hot data, storing the write data in the first region, and otherwise if the write data is classified as cold data storing the write data in the second region.