@Override
  public int[] getDiskDirSizes() {
    if (getDiskStore() != null) {
      return getDiskStore().getDiskDirSizes();
    }
    return diskSizes;
  }
@return int array containing the IDs of the oplogs which will potentially get rolled else null
        if no oplogs were available at the time of signal or region is not having disk
        persistence. Pls note that the actual number of oplogs rolled may be more than what is
        indicated
@since GemFire prPersistSprint1
geode-core/src/main/java/org/apache/geode/internal/cache/LocalRegion.java