Connect to multiple mysql servers. $db = new multi_mysqli(array('host1', 'host2'), 'root', '123456', 'test');

multi_mysqli.php

<?php
/**
 * Multi-Server MySQLi class
 * Givan a list of MySQL hosts, the client will connect to the first available server
 * $servers can be an string for single server, or, for multiple server, use an array or comma-separated list
 */
class multi_mysqli extends mysqli {

    // example from: http://php.net/manual/en/mysqli.real-connect.php
    public function __construct($servers=array(), $username='', $password='', $database='test') {

        try {
            if (!is_array($servers)) {
                if ($servers) {
                    // build array if empty
                    $servers = explode(',', trim(str_replace(' ', '', $servers), ','));
                }
                if (empty($servers)) {
                    throw new Exception('No MySQL servers provided.');
                }
            }

            // init mysqli
            @parent::init();

            // set connect timeout to 1 sec 
            @parent::options(MYSQLI_OPT_CONNECT_TIMEOUT, 1);

            do {
                $server = array_shift($servers);
                $connected = @parent::real_connect(trim($server), trim($username), trim($password), trim($database));

                // next time wait 10 seconds for a connection
                if (!$connected) parent::options(MYSQLI_OPT_CONNECT_TIMEOUT, 10);

            } while (!$connected);

        } catch (Exception $e) {
            die($e->getMessage());
        }

    }
}
?>