boolean validate(Path file) {
    if (HFileLink.isBackReferencesDir(file) || HFileLink.isBackReferencesDir(file.getParent())) {
      return true;
    }
    return StoreFileInfo.validateStoreFileName(file.getName());
  }
This Chore, every time it runs, will clear the unsused HFiles in the data folder.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/BrokenStoreFileCleaner.java