(PECL memcached >= 0.1.0)
Memcached::setMultiByKey — Store multiple items on a specific server
$server_key
   , array $items
   [, int $expiration
  ] )
   Memcached::setMultiByKey() is functionally equivalent to
   Memcached::setMulti(), except that the free-form
   server_key can be used to map the keys from
   items to a specific server. This is useful if you
   need to keep a bunch of related keys on a certain server.
  
server_keyThe key identifying the server to store the value on.
itemsAn array of key/value pairs to store on the server.
expirationThe expiration time, defaults to 0. See Expiration Times for more info.
   Returns TRUE on success or FALSE on failure.
   Use Memcached::getResultCode() if necessary.