Six Feet Up put a failover system in place to prevent downtime in the case of a server outage. Site data is replicated using RelStorage, a relational database backend for the ZODB. This allows the use of the replication services built in to MySQL to replicate the data across two servers.
Search data is replicated using Solr's built-in replication services.
The application servers utilize the ifstated tool to verify that master and slave services are running and that all services are replicating across both servers. If one server were to stop responding, the second server is able to take over using ifstated, then become the master.