I have five nodes behind a load balancer and I'm trying to determine the optimal configuration for a Django based site.
Each node has access to Postgres, mod_wsgi, Apache, Lighttpd, memcached, pgpool2 (for database replication) and glusterfs(for media file replication) and is running Ubuntu 8.04LTS.
So far, the setup is four nodes running Apache/Lighttpd/memcached/pgpool2 all reading/writing to one master node that is running the "master" Postgresql. Each of the four web nodes is also running Postgres for replication from the master via pgpool.
So, my question is: How would you configure this setup and/or what would you change so that there is no single point of failure, if possible?