code: function execute(req, res) {
    this.log.notice('background saving started by pid %s', process.pid);
    function onSave(err) {
      /* istanbul ignore next: not prepared to mock this right now */
      if(err) return this.log.warning('background save failed: %s', err.message);
      this.log.notice('background saving terminated with success')
    }
    Persistence.save(this.state.store, this.state.conf, onSave.bind(this));
    res.send(null, Constants.BGSAVE);
  }
docs: Respond to the BGSAVE command.