code: protected synchronized void incrFileCopyFailures(long incr) {
      if (incr < 0) {
        throw new IllegalArgumentException("Cannot increment by negative value " +
                                           incr);
      }
  
      RaidNodeMetrics.getInstance(RaidNodeMetrics.DEFAULT_NAMESPACE_ID).fileCopyFailures.inc(incr);
      numFileCopyFailures += incr;
    }
docs: Increments the number of decommissioning file copy failures.