We’re trying to ascertain the best way to achieve good redundancy in an enterprise-level utilization of Drupal. Ideally, We would like to have multiple instances of Drupal on different physical hosts/VMs. For instance, if we need to perform maintenance on one host/VM, the site doesn’t go down because there’s always another instance up, or in case of DOS attack, we’d have a better chance of sustaining because we’d have multiple instances running instead of one.
Have others been able to achieved something like this? Any advice, caveats or suggestions?