I am setting up mirror mode masters both in the same data centre, with one slave offsite. Should all the slaves slave from both masters, or should they slave from a load balancer which decides which master is getting the writes at present?
I'm never sure what you mean when you say the replica's should slave from both masters. A replica can only take updates from *one* master for a given tree. Your best option in your case is to set up MMR where only one master is taking writes (mirror mode), and have the replica use a load balanced name between the two masters as its "master" for updates. That should keep data consistent.
--Quanah -- Quanah Gibson-Mount Sr. Member of Technical Staff Zimbra, Inc A Division of VMware, Inc. -------------------- Zimbra :: the leader in open source messaging and collaboration