A method is provided for operating a data storage device comprising a storage medium and a controller configured to control operations of the storage medium. The method comprises determining whether a read-requested data strip is an error data strip, reading a plurality of data strips in a stripe comprising the read-requested data strip when the read-requested data strip is the error data strip, outputting a data strip recovered using the other data strip except the error data strip among the plurality of data strips, and writing the recovered data strip and the other data strips into the storage medium.