public function onOneRandomServer()
    {
        $keys = array_keys($this->getServerConfig());

        do {
            $randServerRank = array_rand($keys);
            if ($redis = $this->getRedisFromServerConfig($keys[$randServerRank])) {
                $this->selectedRedis = array($keys[$randServerRank] => $redis);
            } else {
                unset($keys[$randServerRank]);
            }
        } while (!empty($keys) && empty($this->selectedRedis));

        if (empty($this->selectedRedis)) {
            throw new Exception("Can't connect to a random redis server");
        }

        $this->multiRedis = false;

        return $this;
    }