We have been looking into possibly setting up a MySQL cluster to avoid some of the complexities of a master-slave environment. Does the mediawiki code support MySQL clustering? Has anyone tried testing a cluster with Wikipedia or a smaller db? Also, how does wikipedia currently handle automatic failover of a master-slave transition and then also later the slave-master transition when the master comes back online? What do your scripts do now to deal with that and what kind of monitoring do you to make sure everything is in good health?

Thanks, Chris