Hello Michael,
Thank you for your question and I m happy to answer.
There is an example config ini/dbcluster-config-sample.php
once edited and placed to /wp-content/db-cluster-config.php – it starts to work
In order to use Database Cluster, you need to use WordPress in network mode. You will find an area inside the Database Cache box on the General Settings page. Click ‘Enable database cluster’ to enable the functionality.
As for Memcached, W3 Total Cache recognizes the PHP module, so you need to install PHP Memcached. After that, you will be able to select Memcached as a caching method.
I hope this helps!
Thanks!