public Collection<String> getFamilies() throws IOException {
    FileStatus[] fds =
      CommonFSUtils.listStatus(fs, getRegionDir(), new FSUtils.FamilyDirFilter(fs));
    if (fds == null) return null;

    ArrayList<String> families = new ArrayList<>(fds.length);
    for (FileStatus status : fds) {
      families.add(status.getPath().getName());
    }

    return families;
  }
Returns the set of families present on disk n
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionFileSystem.java