Multiple instances of memcached

Memcached-config

$config= array(
    'default' => array(
        'host' => '127.0.0.1',
        'port'        => 11211,
        'weight'    => 80
    ),
    'server_1' => array(
        'host' => '127.0.0.2',
        'port'        => 11211,
        'weight'    => 50
    ),
    'server_2' => array(
        'host' => '127.0.0.3',
        'port'        => 11211,
        'weight'    => 10
    )