Drupal web cluster with memcached. memcached failover?
If you might want to setup a memcache cluster, consisting of multiple servers. The idea is that you have more than one server in the cluster and if one of the servers is offline for some reason the others will be used.

This is fairly easy to setup and is documented in the memcache module as well, the config could look something like this:

$conf['memcache_servers'] = array(
  '10.0.0.1:11212' =&gt; 'default',
  '10.0.0.2:11212' =&gt; 'default',
  '10.0.0.3:11212' =&gt; 'default'
);
$conf['memcache_bins'] = array('cache' =&gt; 'default');


PHP will handle the clustering, so you wouldn't need to do anything. This means that if a server dies, that cache wont be available, but will automatically be generated on one of the other servers.

One of the ideas with memcache is that you can pool the memory of multiple servers to create a single shared pool.

In your example, you could also use your webservers as a memcache cluster, but that would require that the webservers can talk to each other. Usually when you require multiple servers, you also want to have separate memcache servers, so you can optimize the servers for their specific task.