We have a pretty busy site based on Drupal and I was thinking of introducing some form of clustering for HA and Load balancing.
However, http://drupal.org/requirements says: Drupal supports MyISAM and InnoDB table types. NDB tables (MySQL Cluster) are not supported.
Does that mean I can't use a MySQL cluster to run Drupal? Or did I get that wrong?
Also, how many servers(virtual or physical) would we need to guarantee redundancy for a Drupal site? What software should I be using? I have googled for days and apparently there are many options available so a bit confused here..