This work presents an external memory approach to extract the maximal repeats from whole genome sequences with the statistics of these repeats across classes, where the definition of a class is determined from the statistics to be computed. A heuristic method consisting of a bucket-sort-like approach and the Chinese term extraction approach is adopted. The bucket-sorting method is used to sort the suffixes of DNA sequences stored in files, and the term extraction is used to extract maximal repeats by scanning the sorted suffixes while computing the statistics of these repeats. The statistics of these repeats across classes might be useful for sequence classification and species identification.