public function onOneServer($idServer, $strict = true)
    {
        $redisList = $this->getServerConfig();

        // The server must exist..
        if (array_key_exists($idServer, $redisList)) {
            // and must be available
            if ($redis = $this->getRedisFromServerConfig($idServer)) {
                $this->selectedRedis[$idServer] = $redis;
            } else {
                if ($strict) {
                    throw new Exception('cant connect to redis ' . $idServer);
                }
            }
        } else {
            throw new Exception('unknown redis '.$idServer);
        }

        $this->multiRedis = false;

        return $this;
    }