private void retryOverHdfsProblem(final FileSystem spiedFs) throws Exception {
    generateWALs(-1);
    useDifferentDFSClient();

    try {
      WALSplitter.split(HBASELOGDIR, WALDIR, OLDLOGDIR, spiedFs, conf, wals);
      assertEquals(NUM_WRITERS, fs.listStatus(OLDLOGDIR).length);
      assertFalse(fs.exists(WALDIR));
    } catch (IOException e) {
      fail("There shouldn't be any exception but: " + e.toString());
    }
  }
@param spiedFs should be instrumented for failure.
hbase-server/src/test/java/org/apache/hadoop/hbase/wal/TestWALSplit.java