code: public void setHdfs() {
      assert onICE();
      byte[] mem = memOrLoad();    // Get into stable memory
      _persist = Value.HDFS|Value.NOTdsk;
      Persist.I[Value.HDFS].store(this);
      removeIce();           // Remove from ICE disk
      assert onHDFS();       // Flip to HDFS
      _mem = mem; // Close a race with the H2O cleaner zapping _mem while removing from ice
    }
docs: Set persistence to HDFS from ICE